US President Barack Obama and Russian President Vladimir Putin have urged an immediate end to violence in Syria.
In a joint statement following their first meeting since Putin returned to the presidency, they said they shared a belief that Syrians should determine their own future.
Correspondents say there were no smiles between Obama and Putin during the news conference, and their interactions seemed stiff and strained.
The two countries have been at odds over how to resolve the crisis.
Russia and China have twice blocked US-backed UN draft resolutions critical of Syria.
Both countries argue that pushing the government from power using external pressure is unacceptable.
The meeting of the two leaders on the sidelines of the G20 summit in Mexico came amid unconfirmed reports that two Russian ships were preparing to set sail for Syria.
The two amphibious vessels are apparently on a mission to protect Russian citizens and remove equipment if necessary from the naval base in Tartus.
Meanwhile at least 52 people were killed in the latest violence across Syria.