Mohsen Qamsari, director of international affairs at the company, said foreign carriers are wary of carrying Iranian crude because of insurance issues.
"Currently, only Iranian tankers are authorized to carry Iran's crude and no other country is allowed to carry Iran's oil," he said Sunday.
Iran secured some relief from international sanctions targeting its energy sector in November 2013 when it agreed to curb some of its nuclear research activity. The U.S. government last week extended that relief through the end of November.
Iran is limited to exporting approximately 1 million barrels of oil per day under the terms of the arrangement.
A European court in early July ruled it made a "manifest error" when imposing sanctions on certain Iranian entities tied to the nuclear sector, giving Iran some relief in terms of sanctions against the National Iranian Tanker Co.