MOSCOW — Russia’s foreign minister, Sergey V. Lavrov, said Saturday that there was “no possibility” of persuading President Bashar al-Assad to leave Syria, leaving little hope for a breakthrough in the standoff. He also said that the opposition leaders’ insistence on Mr. Assad’s departure as a precondition for peace talks would come at the cost of “more and more lives of Syrian citizens” in a conflict that has already killed tens of thousands.

Moscow has made a muscular push for a political solution in recent days, sending signals that the Kremlin, one of Mr. Assad’s most important allies, sees a pressing need for political change. As an international consensus forms around the notion of a transitional government, it has been snagged on the thorny question of what role, if any, Mr. Assad would occupy in it.

But after talks in Moscow on Saturday with Lakhdar Brahimi, the United Nations and Arab League envoy on Syria, Mr. Lavrov said that Russia could not press Mr. Assad to give up power. Mr. Lavrov has said that Russia “isn’t in the business of regime change,” but his characterization of Mr. Assad’s stance on Saturday sounded more definitive.

“He has repeatedly said, both publicly and privately, including during his meeting with Lakhdar Brahimi not long ago, that he has no plans to go anywhere, that he will stay in his post until the end, that he will, as he says, protect the Syrian people, Syrian sovereignty and so forth,” Mr. Lavrov said. “There is no possibility of changing this position.”