"There is no date so far ... And current factors do not help in holding it," Assad told al-Mayadeen television on Monday.
Arab League chief Nabil Elaraby said on Sunday after meeting international envoy for Syria Lakhdar Brahimi that the peace conference was scheduled for November 23. Brahimi said the date had "not been officially set".
Assad said opposition groups that had been invited to the talks represented foreign powers rather than Syrians. He criticized Qatar, Turkey, Saudi Arabia, the United States and also the Syrian Muslim Brotherhood, which he described as a terrorist group.
"Many questions about this conference are still on the table," he said.
With Western and Arab countries hoping the talks can start a political transition that would see him leave office, Assad once again indicated he had no intention of quitting, saying he might run for re-election in 2014.
"Personally, I don't see any obstacles to being nominated to run in the next presidential elections," Assad noted when asked if he thought it was suitable to hold the election, as scheduled, in 2014.
Assad inherited power from his father in 2000 and was confirmed in an election in which he ran unopposed. He was re-elected in 2007.
Syria has been gripped by deadly unrest since March 2011, when pro-reform protests turned into a massive insurgency following intervention of western and regional states.
According to reports, more than 100,000 people have been killed and millions displaced.
NTJ/BA