President Vladimir Putin has urged the creation of a broad anti-terror coalition that would include the Syrian government troops.
Addressing the UN General Assembly, Mr Putin said it was a "huge mistake" not to engage the Syrian army in the fight against the Islamic State group.
He also criticised the West for arming "moderate" rebels in Syria, saying they later come to join the Islamic State terror group.
Without naming the United States, he said a "single centre of dominance has emerged after the end of Cold War", and attempts have been made to revise the UN role.
Earlier, President Barack Obama said the United States is willing to work with any nation, including Russia and Iran, to solve the Syrian conflict.
But he said bringing about an end to the four-year civil war means Syrian President Bashar Assad cannot stay in office.
Mr Obama said Mr Assad responded to peaceful protests with repression and killing and would not be able to satisfactorily bring peace to the nation.
Mr Obama called the situation in Syria "an assault on all our humanity".