Macron, making the comments at the start of their bilateral meeting on the summit sidelines, insisted France and China had a "convergence of views" on the conflict.

In the face of a world "made of instabilities, tensions, and increasing wars," Macron said, China and France were in agreement.

"You share like us the same concern following Russia's bellicose and escalatory declarations on nuclear doctrine," said the French president.

"In the same way, in May... we both called for a ceasefire in Gaza, this must now extend to South Lebanon," he added.

Paris, Macron said, would continue to promote "strategic autonomy, precisely to be able to talk with China in complete independence."

Xi in turn told Macron the world was facing growing "risks and challenges" and that "the future trend may be more uncertain and unpredictable," according to video shared by Chinese state media.

But, he said, the two countries' ties had "unique strategic and global significance."

"I am willing to work with you to deepen strategic communication, strengthen mutually beneficial cooperation, and jointly respond to changes and challenges," Xi said.

Macron in May hosted the Chinese leader when he made a state visit to Paris.

Xi and Macron have each been holding numerous bilateral talks on the sidelines of the G20, which gathers the leaders of the world's biggest economies.

While the summit has focused on climate issues and the wars in Ukraine and the Middle East, many of the participants are bracing for an imminent return to the White House of Donald Trump.

Outgoing US President Joe Biden represented his country at the summit but cut a diminished figure as his peers looked past him, politically, to Trump and the "America First" policies the president-elect has pledged.

In comments to journalists late Monday, Macron said Europe had a role to play in supporting "a collective multilateral effort" given increased trade confrontation between the United States and China.