Brahimi said that while some "little adjustments" could be made to the original plan, "it's a valued basis for reasonable political process."
With the opposition offensive gaining momentum in Syria, there is little hope that the initiative would have any more chance of success than it had when it was approved.
Lavrov has said that Moscow is ready to talk to the main Syrian opposition group, even though it had earlier criticized the United States and other Western nations for recognizing the Syrian National Coalition for Opposition and Revolutionary Forces as the legitimate representative of the Syrian people.
On Friday, coalition leader Mouaz al-Khatib rejected the Russian invitation for talks and urged Moscow to support the opposition's call for Assad's ouster. Lavrov said Saturday that al-Khatib's statement was surprising after his earlier contacts with Russian diplomats in Egypt during which the opposition tentatively agreed on a meeting in a third country.
Lavrov said the coalition leader should "realize it would be in his own interests to hear our analysis directly from us."
Lavrov rejected the opposition claim that Russia's continuing weapons supplies to Assad's regime make it responsible for mass killings in Syria, saying that Moscow bears no responsibility for the Soviet-era weapons in Syrian arsenals. He said that defensive weapons such as anti-aircraft missiles that Russia has continued to supply to Damascus couldn't be used in the civil war.
"We aren't providing the Syrian regime with any offensive weapons or weapons that could be used in a civil war," Lavrov said. "And we have no leverage over what the regime has got since the Soviet times."
Georgy Mirsky, a leading Mideast expert with the Institute for World Economy and International Relations, a top foreign policy think tank, said President Vladimir Putin's stand on Syria is rooted in fear that joining international calls for Assad's resignation would make him look weak at home.
"It would look like an inadmissible concession to America, a virtual surrender. The Kremlin would lose its face, look like a loser," said Mirsky.
He wrote in his blog that Putin is resigned to Assad's eventual collapse and the loss of any Russian influence in a future Syria, but firmly opposes international sanctions. That stand allows Putin to tell his domestic audience that Russia has defended its ally until the end against overwhelming odds, said Mirsky.
Jim Heintz contributed to this report.