Russia will continue to oppose attempts by the UN Security Council to sanction military intervention in Syria, Foreign Minister Sergei Lavrov says.
Mr Lavrov also repeated calls for an international conference to implement the peace plan drawn up by UN special envoy Kofi Annan.
He said Moscow would support the departure of President Bashar al-Assad, but only if Syrians agreed to it.
Activists said at least 40 people were killed across Syria on Saturday.
They blamed the Syrian army for the deaths of at least 17 people, including women, during fighting in the southern town of Deraa.
Speaking at foreign ministry in Moscow, Mr Lavrov said that the issue of foreign intervention in Syria was being posed in a "radical and quite emotional way".
He said foreign powers were encouraging the armed opposition to hope that "the Libyan scenario" could be repeated.
"All this is a dangerous game," he said.
"Our position remains unchanged. We will not agree to the use of force being authorised in the UN Security Council.
"That would lead to the gravest of consequences for the whole of the Middle East."
He said the intervention of "external forces" could result in a "catastrophic scenario" that would create an "arc of instability" from the Mediterranean to the Gulf.
Both Russia and China have opposed UN Security Council resolutions condemning the Syrian government for continuing violence.
Mr Lavrov acknowledged that Mr Annan's six-point peace plan had begun to "seriously falter" but said Russia saw "no alternative".
He said that Moscow - which has resisted US-led calls for Mr Assad to stand down - was not opposed to his departure, but only against it being imposed on Syria from outside.
"If the Syrians agree (to Mr Assad's departure) we will only be happy to support such a solution," Mr Lavrov said.
"But we believe it is unacceptable to impose the conditions for such a dialogue from outside."
He also pressed Moscow's idea of an international conference on Syria that would include Iran - an ally of Damascus.
"To say that Iran doesn't have a place because it is already to blame for everything and it's part of the problem... this is thoughtless to say the least from the point of view of serious diplomacy," he said.
The US has accused Tehran of arming Syrian government forces.
The main opposition group, the Syrian National Council (SNC), has also voiced doubts about involving Iran in any negotiations.
The exiled SNC is currently meeting in Turkey to elect a new leader.
The BBC's Steve Rosenberg in Moscow says Russia appears to be increasingly worried by events in the Middle East and feels that the international community isn't taking note of its concerns.
Meanwhile, UN monitors inside Syria have been continuing to investigate an alleged massacre at Qubair last Wednesday.
People in the area told the UN team that everyone in the village near Hama "had died except for a few", UN spokeswoman Sausan Ghosheh told the BBC.
Activists blame militias allied to President Assad while the government accused "terrorists" of killing civilians.