US President George W Bush has said every country must set its own targets to reduce greenhouse gas emissions.
Mr Bush said the US was taking the climate change issue seriously
Correspondents say Mr Bush's comments, at a meeting of the top 16 polluting nations, suggest the US may not agree to any internationally-binding cuts.
He also said combating climate change should not hinder economic growth.
Critics say the US position could dilute attempts to reach a global agreement through the UN, ahead of the expiry of the Kyoto Protocol in 2012.
Mr Bush, who shortly after taking office in 2001 said he would not submit the protocol to Congress for ratification, has opposed mandatory cuts.
He has instead championed voluntary approaches - echoed by China and India.
Addressing the US-sponsored forum on energy security and climate change, Mr Bush said the two issues were "the great challenges of our time" which the US was taking seriously.
He urged the participants to jointly set a long-term goal for reducing the CO2 emissions that were causing the climate to heat up.
"By setting this goal, we acknowledge there is a problem. And by setting this goal, we commit ourselves to doing something about it," Mr Bush said.
He proposed to hold a summit next summer to finalise the goal and other key elements of what he described as "a new international approach" on CO2 gases.
Mr Bush also said such measures would help "advance negotiations under the United Nations Framework Convention on Climate Change".
But he stressed that it was possible to cut emissions without harming economies.
Activists want the US to take the lead in solving the climate crisis
"Our guiding principle is clear - we must lead the world to produce fewer greenhouse gas emissions and we must do it in a way that does not undermine economic growth or prevent nations from delivering greater prosperity for their people," he said.
He said developing clean energy technologies was the key to success, adding that the global demand for energy was expected to increase by 50% by 2030.
The president announced a new international clean technology fund to help developing countries take advantage of new greener methods of generating energy.
But Mr Bush again hinted that the US would not commit itself to mandatory CO2 cuts, despite growing pressure by some of the forum's participants.
"Each nation must decide for itself the right mix of tools and technology to achieve results that are measurable and environmentally effective," Mr Bush said.
The top UN climate official, Yvo de Boer, said he believed the discussions at the conference could feed back into the UN process.
Mr de Boer said it was crucial that industrialised nations committed to an approach that went "well beyond present efforts, given their historic responsibilities and economic capabilities".
Teams from Australia, Brazil, Britain, Canada, the EU, France, Germany, Japan, India, Indonesia, Italy, Mexico, South Africa, South Korea, Russia and the US were taking part in the Washington forum.
The meeting was called by the US as a precursor to UN talks in Indonesia in December, which will seek to launch a successor to the Kyoto Protocol.