"I believe that neither I nor the king of Jordan would dare to entertain the hope that it would be a matter of just a few weeks," Fischer told APA news agency after US Secretary of State John Kerry said Tuesday that Syria could be weeks away from a "big transition".
"We are on the right track, but it would be premature to make a statement about the time needed to solve the problems," he added.
Fischer's statement came after a working lunch with King Abdullah II in Vienna, who did not make any statements to the press.
In a visit to Paris on Tuesday, Kerry said an agreement reached at talks in Vienna between deeply divided countries such as Iran, Russia and Saudi Arabia on a path to elections in Syria was a "gigantic step".
"We are weeks away conceivably from the possibility of a big transition for Syria," he said.
Global diplomats agreed in Vienna Saturday on a fixed calendar for Syria that would see a transition government in six months and elections within 18 months.
A final statement after the meeting said that the goal was to bring Syrian government and opposition representatives together by January 1.
The fate of Syria's President Bashar al-Assad remains unclear, and opposition members have branded the plan unrealistic.
Photo: Office of the Austrian President