In the video captioned "Saving LA-Phase III" posted on his social media, Pratt said he is not leaving town and is going to stay active in local politics.
"You thought you could get rid of me that easily?" Pratt said. "I didn't get in this for political power, I got in this to expose this corrupt machine and nothing's changed."
"And now I don't have to worry about offending CNN viewers. I don't have a campaign to hamstring me now. It's war," he added.
The three-minute video featured clips from movies, news broadcasts and even a UFC fight. Much of it consists of Pratt painting Los Angeles as a negative place to live.
Pratt criticized the remaining candidates, City Councilwoman Nithya Raman and Mayor Karen Bass.
"Angelenos are now stuck with two morons responsible for all their problems and now have to choose between dumb and dumber," Pratt said, as images of Raman and Bass appeared.
He also said that "every problem that plagues Los Angeles because of these two corrupt communists is going to accelerate" under their leadership.
Pratt's goal has not changed, he said, and he remains focused on stopping "these commie animals."
"If you think we uncovered a lot of fraud and evil in the campaign, just wait," Pratt said.
He went on to say that they have a recording of one of the candidates "doing or saying something that would make her resign in shame," but did not directly say whether it was of Bass or Raman.
He calls them both out while looking directly at the camera, saying, "So, Karen, Nithya, ask yourself. Is it possible that one of your employees may have a recording of you doing or saying something that would force you to resign in disgrace?"
Pratt used the opportunity to discuss the Palisades Fire, which destroyed his home and was a recurring topic during his campaign.
"Hope you sleep well at night over the next five months, because you know who hasn't slept well at all for the last 17 months? My mom. All my neighbors in the Palisades,'' he said.
He also claimed major developers, hoteliers, business owners and entrepreneurs have told him they are leaving the city, which he argued would lead to more restaurant closures and less tax revenue.
"That means the city has to cut services. More potholes, less firefighters, less police patrols, more criminals, more drug addicts terrorizing your communities," Pratt said.
"You have no idea how bad things are about to get for the city, look at this place already," he added. "The city is a mess and you're about to reward the arsonist who torched the place with four more years of destruction."
Pratt competed against Bass and Raman in the primary election for a spot in the November runoff. He was eliminated after failing to secure enough votes to advance.
His video message comes just one day after Raman made a pledge to his supporters to deliver on the change they want in an effort to be their candidate come November.
The election was not a vote of confidence in Bass, who, according to incomplete returns, received under 35% of the vote, a vulnerable position for an incumbent. Still, she remains ahead of Raman with a more than 44,000 vote difference.
Raman holds a lead of more than 29,000 votes over Pratt in the latest election results, with 246,333 votes to Pratt's 216,783.
Raman, who previously endorsed Bass for reelection, had been running in third until Sunday, but she gained more votes with every update provided by election officials in Los Angeles since June 2, primary day.
Eyewitness News reached out to Raman's campaign, who had no comment about Pratt's video.
The Bass campaign did not respond to our request for comment.
Pratt's candidacy drew national attention due to his celebrity status and outspoken criticism of liberal leadership in a heavily Democratic city, but that attention did not translate into sufficient support at the polls.
Angelenos will decide in November whether Bass keeps her position as mayor or if voters turn the page and elect Raman as the new leader for the city.