Foreign Minister Sergey Lavrov told journalists during a press conference that the West should help encourage those rebels who don't harbor "extremist or terrorist views" to join the talks to settle the 2 1/2-year conflict.
"The goal now is to waste no more time and seat those reasonable opposition members at the discussion table with the government," said Lavrov. "Those who aren't thinking about founding a caliphate on Syrian territory, who aren't thinking only about how to seize power and then use it at their own discretion."
The U.N. Security Council, which last week endorsed an international plan for Syria to destroy its chemical weapons, has called for a peace conference to be convened as soon as possible.
Russia has been Assad's key ally, protecting him from the U.N. sanctions. Moscow has initiated the chemical disarmament plan for Syria to avert a U.S. military strike against Syria over a chemical attack against Syrian civilians, which the West has blamed on Assad's forces.
The fighting that began in March 2011 has claimed over 100,000 lives and forced millions of Syrians to flee the violence, according to the United Nations.