President Barack Obama says the US "does not seek to contain" China's rise as a big player on the world stage.
"The rise of a strong, prosperous China can be a source of strength for the community of nations," Mr Obama said in a speech in Japan's capital, Tokyo.
Better US ties with Beijing do not mean a weakening of relations with US allies in the region, he said.
Describing himself as the first "Pacific" US president, he said the US was committed to the area's security.
Mr Obama is now in Singapore, where he is to attend an Asia-Pacific economic summit.
His trade representative Ron Kirk, who is already at the Apec meeting, says the US wants barriers to trade and investment removed to promote an open global trade system.
Mr Obama will round off his week-long Asian tour with stops in China and South Korea.
North Korea talks
Mr Obama told the gathering in Tokyo that Washington's commitment to the region's security was "unshakeable", despite its commitments in Iraq and Afghanistan.
1. Friday 13: Arrived in Japan
2. Saturday 14: To Apec summit in Singapore
3. Sunday 15: Has talks with Russia's President Medvedev before leaving for China
4. Tuesday 17: Summit in Beijing with Chinese President Hu Jintao
5. Wednesday 18: Ends tour in South Korea
He said the US would pursue "pragmatic co-operation" with Beijing on issues of mutual concern.
He also warned that he would not waver from raising human rights concerns with Beijing, but did not mention specific concerns, such as Tibet.
The US president called for more assistance from China to thwart the ambitions of North Korea, and warned there would be tough, unified action by the US and its Asian partners if Pyongyang failed to abandon its nuclear weapons programme.
Mr Obama again called on North Korea to return to six-party talks on the issue, adding the US would not be "cowed" by Pyongyang's nuclear threats.
He also called on Asian leaders to pursue balanced economic growth.
On the issue of economic co-operation, Mr Obama challenged Asian countries to break their dependence on exports to the US and to pursue "balanced" and sustainable economic growth.
"We must strengthen our economic recovery, and pursue growth that is both balanced and sustained," he said. "We simply cannot return to the same cycles of boom and bust that led us into a global recession."
He said the US would pursue a new economic strategy that would mean "saving more and spending less".
He urged Asian leaders to break their dependence on exports to the US market and to open up their markets to speed up a global economic recovery.
Mr Obama arrived in Tokyo on Friday and met Japanese Prime Minister Yukio Hatoyama.
The two leaders agreed on the need to renew their countries' strained alliance and pledged to work quickly to resolve a dispute over the US military base in Okinawa.
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