The president also disputed criticism that the United States was feuding with other nations about the need to pump more money into economic stimulus policies, saying any differences are “vastly overstated.”
Obama prodded nations to spur growth and work together on regulatory reform, and not fall into the kind of protectionism and other mistakes that helped fuel the Great Depression.“That is a mistake that we cannot afford to repeat,” Obama said alongside British Prime Minister Gordon Brown.
Asked about whether the US was to blame for causing the economic slide, Obama said he preferred to look ahead, not back. He said he had no worries about the stability of the US economic system.
"I think that there is a vibrancy to our economic model, a durability to our political model, and a set of ideals that has sustained even through the most difficult times," Obama said.
Brown, too, sought to play up consensus. "As President Obama has said, never before has the world come together in this way to deal with an economic crisis," the prime minister said.
"We are within a few hours, I think, of agreeing a global plan for economic recovery and reform," he added.
Obama sought to put a human face on the suffering economy, often turning his exchange with reporters back to those who have lost their jobs and their homes. Pressed about whether consumers should be saving or spending during the crisis, Obama said that was a decision for families.
But he added that people should consider spending now to invest in their future.
"Basing decisions around fear is not the right way to go," Obama said. "We are going to get through this difficult time."
Obama is meeting separately later with Russian President Dmitry Medvedev and Chinese President Hu Jintao. Officials in both countries have called for a new global currency to end the dollar's dominance.
Dramatic in itself, the suggestion is also a sign of broader questions about whether US status in the world could be threatened by the rise of a competing power bloc. Still, it's not likely that the new currency idea will gain immediate traction.
Both meetings are being held at the US ambassador's residence, with the news media only allowed into the room before the talks take place and without the ability to ask questions.
The G-20 meetings open with a working dinner Wednesday night and continue throughout Thursday. Before then, Obama is squeezing in talks with Brown's main rival -- David Cameron, the leader of Britain's opposition Conservative Party. In the afternoon, Obama heads to Buckingham Palace for an audience with Queen Elizabeth II. With US-Russia relations having deteriorated in recent years to lowest point since the early 1980s, the Obama administration has announced its desire to "press the reset button." The Kremlin has made clear it believes it is up to Washington to open the effort with concessions.
Obama has indicated less enthusiasm than predecessor George W. Bush for a proposed new US missile defense system based in Eastern Europe, an idea that has enraged Russia.
The White House said Wednesday that Obama and Medvedev would announce talks to limit the number of nuclear warheads when they meet in London. White House spokesman Robert Gibbs said they would be the first major arms control negotiations since 1997. Gibbs says the two countries want to reduce that number but the leaders have not settled on a specific goal.
Obama's talks with Hu are sure to address Beijing's concerns about the safety of its position as Washington's biggest foreign creditor, with about $1 trillion in US government debt. For the US, there are fears that any Chinese flight away from those investments would erode the US ability to spend more on recession-fighting.
For China, unusually forthright of late in challenging the US-led global order, its goal is a greater say in how international finance is regulated and managed.
Beijing and Washington also have sparred over military matters.