Anti-regime activists say more than 17,000 people have been killed, and the government says it has lost more than 4,000 security officers. It does not provide numbers of civilian dead.
International diplomacy has failed to stop the violence, and world powers remain deeply divided over who is responsible and how to stop it. The U.S. and many Western nations have called on Assad to leave power, while Russia, China and Iran have stood by the regime.
Lavrov objected to the text of a Western-backed resolution that calls for sanctions and invokes Chapter 7 of the U.N. Charter, which can be enforceable militarily.
He said Russia had been told that if it opposed the resolution, Western nations would not extend the mandate of a U.N. mission sent to Syria to monitor a cease-fire.
"We consider it to be an absolutely counterproductive and dangerous approach," Lavrov said.