France's President Francois Hollande gives a statement about French intervention in Syria during the 70th UN General Assembly in New York on September 27, 2015. [Photo/Agencies]

Hollande said he would support those efforts and France would hold bilateral meetings throughout the week with key players in the Syria crisis before a summit with Russian President Vladimir Putin in Paris on Friday.

"France doesn't sideline anybody, but the future of Syria cannot pass through President Bashar al-Assad," he said.

Two French diplomatic sources said the idea of creating a buffer zone in northern Syria was one issue that could be discussed over the coming days.

"It's one of the parameters being looked at," one source said.

French Foreign Minister Laurent Fabius said on Saturday Paris was still seeking clarification on Russia's military build-up in Syria, adding that if it went beyond defending its interests in the country it could complicate any political transition.

The United States is leading two different coalitions carrying out air strikes in Iraq and Syria, but Hollande repeated that for the moment Paris would make its decisions to strike in Syria independently, albeit in coordination with Washington.

France was ready to join air strikes on military installations in Syria in 2013 in response to a massive chemical weapon attack before US President Barack Obama turned against it after Assad agreed to abandon his chemical arsenal. That left French officials cautious of US intentions in Syria.