Cameron told lawmakers he was "acting decisively to restore order on our streets," as police raided houses to round up suspects from four nights of unrest in London and other English cities.
Steve Kavanagh, the deputy assistant commissioner of London's Metropolitan Police, admitted the force initially did not deploy enough officers to control the outbreak of violence, saying "it is clear we did not have enough numbers on duty to deal."
Cameron also acknowledged that police had been overwhelmed by mobile groups of looters in the first nights of the rioting and said authorities were considering new powers, including allowing police to order thugs to remove masks or hoods, evicting troublemakers from subsidized housing and temporarily disabling cell phone instant messaging services.
He said the 16,000 police deployed on London's streets to deter rioters and reassure residents would remain through the weekend. "We will not let a violent few beat us," Cameron said. While Britain's streets were clear of looters for a second night in a row, the toll of the riots continued to climb. A 68-year-old man who was attacked during rioting in west London as he tried to put out a fire died late Thursday, police said in a statement.
Richard Mannington Bowes had been in a coma since Monday. Police said a murder investigation has now been opened into his death.
Lawmakers were summoned back from their summer vacations for an emergency session of Parliament on the riots as government and police worked to regain control, both on the streets and in the court of public opinion.
During a session lasting almost three hours in which he faced 160 questions from lawmakers, Cameron promised tough measures to stop further violence and said "nothing should be off the table." He said that included water cannon and plastic bullets - though senior police have said they don't feel the need to use those at the moment. He also said officials would look at "whether there are tasks that the army could undertake that would free up more police for the front line."
Cameron said he would seek American advice on fighting the street gangs he blamed for helping spark Britain's riots.
He told lawmakers that he would look to cities like Boston for inspiration, and mentioned former Los Angeles, New York and Boston Police Chief William Bratton as a person who could help offer advice.
Bratton said in a statement he'd be "pleased and honored" to provide services and counsel in any capacity, adding that he loves London and has worked with British police for nearly 20 years.
Cameron told lawmakers he wanted to look at cities that had fought gangs "by engaging the police, the voluntary sector and local government."
"I also believe we should be looking beyond our shores to learn the lessons from others who have faced similar problems," Cameron said.
He said the government, police and intelligence services were looking at whether there should be limits on the use of social media sites like Twitter and Facebook or services like BlackBerry Messenger to spread disorder.
BlackBerry's simple and largely cost free messaging service was used by rioters to coordinate their activities, Cameron's office said.
Britain's Home Office said it planned to hold talks with police chiefs, Twitter, Facebook and Blackberry manufacturer Research In Motion Ltd.
Facebook looks forward to meeting with the home secretary, the company said in a statement, adding that it has taken steps in recent days to ensure that any credible threats of violence are removed from the social networking site.
Government officials said they were discussing with spy agencies and communications companies whether messaging services could be disabled in specific areas, or at specific times.
Authorities are considering "whether it would be right to stop people communicating via these websites and services when we know they are plotting violence, disorder and criminality," Cameron said.
Cameron said that, in the future, police would be able to order people to remove masks, hoods or other face coverings when they suspect them of concealing their identity to carry out a crime. Currently, police must seek approval from a senior officer.
Communities Secretary Eric Pickles confirmed that powers that allow authorities to evict convicted criminals from government-subsidized housing will be strengthened. Authorities have the power to eject someone from social housing if they commit a crime, but only if the offense is in their own neighborhood.
Pickles said he hoped the power would be more widely used, and that it would apply to crime committed anywhere.
A program that can ban gang members from meeting together, loitering in certain places, or displaying gang insignia will also be extended, he said.
Some lawmakers urged Cameron to take even tougher measures. Conservative Party lawmaker Peter Tapsell said he recalled law enforcement officers in Washington, D.C. in 1971 rounding up anti-Vietnam war demonstrators and imprisoning them in a sports stadium. Tapsell asked Cameron if London's Wembley Stadium, the country's showpiece soccer arena, could be used. Cameron insisted the stadium would be used only for "great sporting events."
Parliamentary authorities confirmed Thursday that a petition calling for those convicted of offenses during the riots to lose welfare payments could be debated by lawmakers. Earlier this month, Britain began an initiative under which online petitions with at least 100,000 signatures will be considered for debate in the House of Commons.
Authorities said the petition crossed the threshold on Thursday - the first to do so - and would now be studied by a committee that decides on Parliament's business.
Britain's riots began Saturday when an initially peaceful protest over a police shooting in north London turned violent. That clash triggered wider lawlessness that police struggled to halt.
Across London, and then in cities throughout England, rioters set stores on fire and looted shops for sneakers, bicycles, electronics and leather goods. For the first couple of nights there were too few police on the streets to challenge them.
That changed Tuesday, when 16,000 officers were deployed on London's streets - almost three times the number of the night before.
Police swooped on houses across London on Thursday, detaining suspects and retrieving stolen goods. The number of people arrested since Saturday rose to 1,009, with 464 suspects charged.
Birmingham remained in focus as tensions remained high after three men were killed in a hit-and-run incident as they took to the streets to defend shops from looting. Police on Thursday arrested three more men on suspicion of murder - a 16-year-old, a 17-year-old and a 26-year old. A 32-year-old man arrested a day earlier was released on bail.
Scenes of ransacked stores, torched cars and blackened buildings have frightened and outraged Britons just a year before their country is to host next summer's Olympic Games, bringing demands for a tougher response from law enforcement and calls for the government to scrap plans to cut police budgets.
Cameron's Conservative-led government is slashing 80 billion pounds ($130 billion) from public spending by 2015 to reduce the country's swollen budget deficit - measures that include curbing police budgets. A report last month said the cuts will mean 16,000 fewer police officers by 2015.
Normality was being restored in London Thursday, although soccer authorities announced that Tottenham Hotspur's season-opening match against Everton on Saturday was being postponed.
Nine other Premier League matches due to be played this weekend across the country are due to go ahead.
As authorities attempted to dispense swift justice to rioters, there were chaotic scenes at courthouses, several of which sat through the night to process scores of alleged looters and vandals, including an 11-year-old boy.
The defendants, mostly young but otherwise diverse, included a teenage ballerina, a university English student from a prosperous commuter town and Natasha Reid, a 24-year-old university graduate who admitted stealing a TV from a looted electronics store in north London. Her lawyer said she had turned herself in because she could not sleep because of guilt.
Also due to appear in court were several people charged with using Twitter and Facebook to incite violence.
Cassandra Vinograd and David Stringer in London, and Shawn Pogatchnik in Birmingham, England, contributed to this report.