He also said other countries could not just rely on Washington to help boost the global economy.
"If there's going to be renewed growth, it can't just be the United States as the engine," he said.
"Everybody is going to have to pick up the pace and I think that there is a recognition based on the conversations I've had with leaders around the world that that is important."
Both leaders sought to downplay differences between world leaders over fiscal stimulus plans, with Brown saying the level of international co-operation over the crisis was unprecedented.
Obama said there was "enormous consensus" among leaders of developed and developing nations.
Jonah Hull, Al Jazeera's correspondent in London, said: "Whether this rift [over economic plans] is as serious as it's been portrayed is now being called into question.
"They were both at pains to point out that in terms of fiscal stimulus ... they made it very clear that it was being embraced around the world, pointing out that $2 trillion had been injected into the global economy."
While the US president wants member states to inject more money into programmes aimed at kickstarting their flagging economies, France and Germany have said that greater regulation of the financial markets is a more pressing need.
"Obama does want increased spending. He has been talking about putting together a big stimulus package, as the US and China have already done," Rob Reynolds, Al Jazeera's senior Washington correspondent, said.
"It looks, however, that he has scaled back considerably on his expectations for receiving any commitments on specific figures at the London meeting."
Obama later met with Hu Jintao, the Chinese president, and said he had accepted an invitation to visit China later this year.
The White House said Obama and Hu had agreed to "intensify co-ordination and co-operation on global economic and financial issues.''
The two countries also agreed to form a US-China Strategic and Economic Dialogue group.
Hillary Clinton, the US secretary of state, and Timothy Geithner, the country's treasury secretary will represent the United States during those talks.
Nicolas Sarkozy, the French president, has said that the summit needs to examine ways to regulate the global financial system.
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"The world expects that we rebuild, together, a new form of capitalism, better regulated, with a greater sense of morality and solidarity," he said in comments released by the president's office on Wednesday.
"This crisis is not the crisis of capitalism. On the contrary, it is the crisis of a system which has drifted away from the most fundamental values of capitalism," he said.
Paris and Berlin are committed to improving global economic confidence through greater oversight of the financial system rather than through pumping money into their respective domestic economies, Reynolds said.
"They want to restructure global finance with greater international regulation of banks, hedge funds, offshore tax-havens and executive bonuses," he said.
But Mark Burgess Watson, chief operating officer of Japan Invest, an equity research firm in Hong Kong, said that China's recent call for the dollar to be dropped as the world's main reserve currency could be a sticking point in relations between Beijing and Washington.
"I think the posturing has to end. China has slightly overplayed its hand and, I think, in signalling its interest in pursuing a world reserve currency, rather than accepting the dollar status-quo, smacks rather of opportunism and muscle-flexing to take advantage of US weakness," he said.
"I think the two countries need to withdraw into positions that are mutually acceptable."