DUBAI (Reuters) -Talks in Vienna on reviving the 2015 nuclear deal between Iran and world powers have made “significant progress”, Iranian foreign ministry spokesman Saeed Khatibzadeh said on Monday. Separately, Iran’s top security official Ali Shamkhani said talks with European negotiators were ongoing and would continue while negotiations with the United States were not on the agenda because they would not be the source of “any breakthroughs”. Indirect talks between Tehran and Washington have been held in Vienna since April amid fears about Tehran’s nuclear advances, seen by Western powers a…