"The demand by the United States to hand over chemical weapons to international control in two or three weeks is simply unprofessional," Pushkov wrote on Twitter on Saturday.
He added "In Syria there are at least 42 storage facilities, some of them in battle zones."
US officials said Friday that the White House expected that it would take around two weeks to discover whether the Russian-led initiative to take President Bashar al-Assad's chemical weapons under international control was viable.
The United States and Russia are negotiating over how much time Syria can be given to comply with the terms of the international convention banning chemical weapons and declare its full stockpile.
US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov were set to meet for a third day of complex talks in Geneva seeking to reach a deal on eliminating Syria's chemical weapons stocks.
The rhetoric of war against Syria first gained momentum on August 21, when the militants operating inside the country and the foreign-backed Syrian opposition claimed that over a thousand people had been killed in a government chemical attack on militant strongholds on the outskirts of Damascus.
The Syrian government categorically rejects the allegation, saying the militants carried out the attack to draw in military intervention.
Syria has been gripped by deadly unrest since 2011. According to reports, the Western powers and their regional allies -- especially Qatar, Saudi Arabia, and Turkey -- are supporting the militants operating inside Syria.
RA/HH