Iran's role, if any, in the Jan. 22 conference in Geneva has yet to be determined, RIA Novosti reported Thursday.
Russia and the United States, as organizers of the summit, must approve the nations that can attend. Washington and Syrian rebel groups say they are opposed to Tehran's presence, charging Iran has supplied Syria with troops and weapons.
Tehran has said it opposes an agreement reached in 2012, calling for rebel forces and the regime of Bashar Assad to form a transitional government.
U.S. Secretary of State John Kerry said this week Iran might be able to contribute from he sidelines, but could not participate in the talks. Iran has rejected having a minor role.
A U.N. spokesman said Iran was not invited to the first round of talks, but that U.N. Secretary General Ban Ki-moon believes Tehran should participate.
Delegates from 26 counties are expected to attend the summit, U.N.-Arab League envoy Lakhdar Brahimi said in December.