Speaking in Damascus after meeting Syrian President Bashar al-Assad, Ryabkov also kept up Russian criticism of a report by UN investigators on a poison gas attack in the suburbs of Damascus on Aug. 21.
Western governments say the UN report confirmed Assad's forces were behind the attack, which led the United States to threaten punitive military strikes before Washington and Moscow reached a deal for Syria to abandon its chemical arms.
Russia says it suspects rebels staged the attack to provoke military intervention, and Ryabkov accused the investigators of all but ignoring evidence presented by the Syrian government that he said supported rebel culpability.
"We are disappointed that there is no due attention paid to this evidence in the report which the (UN) group presented in New York earlier this week," he told reporters in Damascus in televised remarks.
"One cannot be as one-sided and as flawed as we have seen, laying the full (blame for the) incident in Ghouta upon the Syrian government," he said, referring to Western nations' interpretation of the report on the Aug. 21 attack.
He said the report was limited in scope and reiterated Russian calls for further investigation that would include accounts from sources such as the Internet and government evidence of alleged chemical arms use in the days after Aug. 21.
The U.S.-Russia deal, reached on Saturday, calls for Syria to account fully for its chemical weapons within a week and for the removal and destruction of the entire arsenal by mid-2014.
Diplomats from the permanent UN Security Council members - Russia, the United States, Britain, France and China - began talks on Tuesday on a resolution intended to support the deal.
Diplomats have said initial Western drafts called for giving Syria an ultimatum to give up its chemical weapons or face "necessary measures".
Ryabkov said the resolution should support an expected decision by the Organization for the Prohibition of Chemical Weapons' Executive Council setting out procedures for dealing with the chemical weapons "and nothing more than that" beyond providing an element of security for OPCW activity in Syria.
