Russian Prime Minister Dmitry Medvedev has warned that sending more foreign ground troops into Syria will result in "a full-fledged, long war".
He hit back at the US Secretary of State John Kerry, who has suggested more countries could enter the conflict if diplomatic efforts fail to reach a solution.
The Russian PM has also said ongoing tensions between Russia and the West have plunged the world into "a new period of Cold War".
French Prime Minister Manuel Valls has called on Russia to stop bombing civilians in Syria, saying it is crucial for achieving peace in the country.
In a speech at a security conference in Munich, Mr Valls said: "France respects Russia and its interests ... But we know that to find the path to peace again, the Russian bombing of civilians has to stop".
Russian Prime Minister Dmitry Medvedev rejected claims Russia has bombed civilians in Syria, saying there was "no evidence" to back the accusations.
Syrian President Bashar al-Assad has vowed to regain control of the entire country but warned it could "take a long time".
Marathon talks agree a partial ceasefire but fail to secure an end to Russian bombing, while rapid humanitarian aid won't reach all Syrians.