The Syrian government says Bashar al-Assad's position as president is not up for negotiation at peace talks, calling such demands by the opposition "delusions and dreams".
The statement, issued by the foreign ministry via the SANA news agency on Wednesday, said a delegation would go to planned Geneva II talks in January, but Assad would not "surrender power".
"The age of colonialism, with the installation and toppling of governments, is over. They must wake from their dreams," the statement said. "If they insist on these delusions, there is no need for them to attend Geneva II."
"The official Syrian delegation is not going to Geneva to surrender power."
The government delegation would convey "the wishes of the Syrian people, foremost among them the elimination of terrorism" - a reference rebels fighting Assad's regime.
The Syrian statement was the first formal response from Damascus to this week's announcement of the talks.
The Geneva II talks, being pushed by the UN, aims to create a transitional government to end the civil war.
The Syrian National Coalition opposition group will also attend the long-delayed talks in January, the group's president, Ahmad Jarba, said on Wednesday.
In an interview with Reuters and the Associated Press, he also said regional power Iran should only be allowed to attend if it stopped taking part in the bloodshed in Syria and withdrew its forces and proxies.
The coalition said previously it was ready to attend if humanitarian aid corridors were set up and political prisoners released.
It insists that President Bashar al-Assad can play no future role in Syria.
"We are now ready to go to Geneva," Jarba said on a visit to Cairo, adding that the opposition viewed the Geneva talks as a step to a leadership transition and a "genuine democratic transformation in Syria".
"There is no way that the individual responsible for the destruction of the country can be responsible for building the country," said Jarba, referring to Assad.
Meanwhile, Iran's Foreign Minister, Mohammad Javad Zarif, said on Wednesday that Tehran and Ankara would press for a ceasefire in Syria ahead of peace talks planned for January, the Mehr news agency reported.
"All our efforts should be carried out to finish the conflict and reach a ceasefire even before Geneva II," Zarif said after a meeting with his Turkish counterpart Ahmet Davutoglu.
"Iran and Turkey have similar standpoints on several issues, including that there is no military solution to the Syrian crisis."
On Tuesday, the rebel Free Syrian Army's commander, General Salim Idriss, said his forces would not agree a ceasefire to smooth the way for talks.