Iran is neither optimistic nor pessimistic about the outcome of the Vienna nuclear talks on Tuesday, but feels confident about being on the right track to revive the 2015 nuclear deal, Iranian government spokesman Ali Rabiei told reporters.

"We are not optimistic nor pessimistic about the outcome of this meeting now, but we are confident that we are on the right track, and if America's will, seriousness and honesty is proven, it could be a good sign for a better future for this agreement and ultimately its full implementation," Rabiei said.