He also warned people in Hawaii, Guam, American Samoa and the West Coast to heed the instructions of local authorities about evacuations and other measures in advance of a tsunami moving across the Pacific Ocean.
"We can't control nature, but we can and must be prepared for disaster when it strikes," he said in a statement at the White House.
The Pacific Tsunami Warning Center issued a tsunami warning - its highest alert - for Hawaii. The first waves were expected to arrive in Hawaii late afternoon EST. A lower-grade tsunami advisory was in effect for the coast of California and an Alaskan coastal area.
The Navy was moving more than a half dozen vessels Saturday to try to avoid damage from the tsunami.
A frigate, three destroyers and two smaller vessels were being sent out of Hawaii's Pearl Harbor in a cruiser out of the base at San Diego in California, said Lt. Myers Vasquez, a Navy spokesman in the Pentagon. The ships are safer out on the sea than if they were tied to piers where they could be banged around by the waves, meaning damage to the vessels as well as the piers, he said.
Before he spoke, Obama had a 20-minute conference call with staff and Cabinet members who updated him on conditions in Chile and on the tsunami. Participants included Secretary of State Hillary Clinton and Homeland Security Secretary Janet Napolitano.
"The United States stands ready to assist in the rescue and recovery efforts and we have resources that are positioned to deploy should the Chilean government ask for our help," Obama said. Chile's president, Michelle Bachelet, said her government has not asked for assistance from other countries.
Clinton planned to leave Sunday for a previously scheduled trip to the region. Her itinerary included more than a day in Chile, but it was unclear Saturday whether she would stick to it.
The U.S. Embassy in Chile was working to learn the whereabouts of U.S. citizens in Chile, both diplomatic employees and other Americans who may have been living there or visiting, State Department spokeswoman Megan Mattson said.
There were no reports of U.S. casualties, and the U.S. military said it had no reports that any of its forces had been affected either on land or at sea.
The State Department advises Americans seeking information on family and friends in Chile to contact the Bureau of Consular Affairs at 1-888-407-4747.
There are 118 embassy employees in Chile. It was unclear how many Americans there are throughout Chile, but an estimated 1,000 live in and near Concepcion, which is Chile's second-largest city and only 70 miles from the earthquake's epicenter.
A helpline for those seeking information on family in Chile has been set up: 1-888-407-4747
