Iran would rather hold talks on its nuclear programme in Iraq or China, rather than the most-likely venue of Istanbul.
Meetings with officials from the five permanent U.N. Security Council members and Germany are due to take place on April 13.
Syria is the source of tension between Iran and Turkey – with Tehran supporting President Bashar al-Assad and Ankara criticising him. Iran also wants to prevent Turkey’s influence growing in the Middle East.
Tehran is proposing that the negotiations take place in Baghdad and Iraqi authorities have already indicated they are supportive.
Other options being put forward are Beijing, Damascus and Beirut.
The last time Iran met the delegation in Istanbul 14 months ago, no agreement was made.
Despite western fears of an atomic bomb, Tehran continues to insist its nuclear programme is for peaceful purposes.