Sergey Markov's comments came after U.N. Special Envoy for Syria Staffan de Mistura announced Wednesday "a pause" in discussions aimed at resolving Syria's years-long war, explaining that "dramatic circumstances on the ground in Syria" strip the talks of "any meaning."
Russia has stepped up its military support in recent days, using airstrikes to boost a Syrian government offensive on the city of Aleppo.
Speaking at a donors conference for Syria in London on Thursday, United Nations Secretary-General Ban Ki-moon blamed the collapse of talks, in part, on Russia's military intervention in Syria.
"It is deeply disturbing that the initial steps of the talks have been undermined by the continuous lack of sufficient humanitarian access, and by a sudden increase of aerial bombings and military activities within Syria," he said.
Regime forces, backed by the Russian airstrikes, were closing in on two besieged towns outside Aleppo on Wednesday, according to Syrian State TV.
The main opposition delegation in Geneva canceled a planned meeting with Mistura, denouncing the escalation in violence.
Markov, a former lawmaker in President Vladimir Putin's United Russia party, told CNN's Christiane Amanpour that Turkey and Saudi Arabia, which publicly support the Syrian opposition, must understand over time they "will have to go to negotiation."
The longer they wait, Markov said, the more victorious Assad will be.
Saudi Arabia "needs to see the Syrian army taking more and more territory, and their allies in Syria will have to sit down at the table with some Assad envoys," he said.
Mistura said he hopes to restart negotiations on February 25.