US President Joe Biden says the Group of Seven nations have agreed a united approach to China that calls for diversifying supply chains to reduce dependence on one country, and hinted that he could speak with China's president soon.

"We're not looking to decouple from China. We're looking to de-risk and diversify our relationship with China," Mr Biden said on Sunday after a three-day summit with G7 leaders.

He said G7 nations were more unified than ever in terms of "resisting economic coercion together and countering harmful practices that hurt our workers".

G7 leaders outlined a shared approach to "de-risk, not decouple" economic engagement with China in a Saturday communique, prompting China's embassy in Japan to urged the G7 to stop creating confrontation and division.

Despite the reaction, Mr Biden said he expected a thaw in frosty relations with China "very shortly" after strains caused by an incident earlier this year when the US shot down a Chinese balloon that flew over sensitive military sites.

He added that he had agreed with Chinese President Xi Jinping during a G20 summit in Bali last year to keep communications open, but everything changed after "this silly balloon that was carrying two freight cars worth of spying equipment".

Mr Biden suggested a shift in US-China relations could occur soon, echoing his comment to reporters before his departure.

"In terms of talking with them, I think you're going to see that thaw very shortly," Mr Biden said.

China-Taiwan tensions

On the issue of tensions between China and Taiwan, Mr Biden said there was a clear understanding among most of the allies that if China were to act unilaterally against the self-governed island Taiwan, there would be a response.

"We're not going to tell China what they can do," he said.