Washington: The US State Department said on Tuesday that it was premature for Moscow to invite Syrian opposition to attend talks in Russia.
Acknowledging having seen reports that Russians will hold a meeting between the Syrian government and members of the opposition next week, US State Department spokeswoman Elizabeth Trudeau told reporters that "We think it's premature".
"There will be a time and place when the opposition groups will be presented," Trudeau said at a daily press briefing. "We just don't think we're there yet."
She urged Russia "to focus its efforts on ISIL (another acronym for the Islamic State militant group) and to use its influence with the Assad regime to support a genuine political transition" in Syria.
"We don't believe we're ready for the discussions until the international community can reach a greater consensus about the path forward," the spokeswoman said.
For now nations involved in diplomatic efforts on Syria's conflict should focus on what was agreed on in talks in Vienna, she said.
Friday's international meeting on Syria did not produce any agreement over the future of Syrian President Bashar al-Assad, although key players found some common ground over the solution for the war-torn country.
After hours of talks in the Austrian capital, key players agree to initiate a diplomatic process to find a solution to the Syrian crisis.
However, at a joint press conference, Russian Foreign Minister Sergei Lavrov and US Secretary of State John Kerry both acknowledged differences remain over the future of al-Assad, but saying the gap would not stand in the way of ending the war in Syria.
Both the United States and Russia are conducting airstrikes against the Islamic State (IS) militant group in Syria.
The US, which opposes Moscow's backing of al-Assad, has been criticizing Russia's over month-long airstrikes only focused on al-Assad's opponents, rather than the IS.