The U.S. government is taking a wait-and-see approach to the "rumors" of an oil-for-goods deal between Russia and Iran, a State Department spokesperson said.

Iran and Russia have cooperated in the nuclear energy sector and more recently mulled the prospects of working on a deal for Iran to deliver oil to Russia.

"In the past [we] had said we saw nothing at that time to indicate any real progress had been made in terms of that kind of agreement," spokesperson Marie Harf said during a Wednesday briefing. "There are lots of rumors about what may actually transpire from this, so we will watch and see."

Iranian President Hassan Rouhani is scheduled to meet Friday in Tajikistan with Russian President Vladimir Putin.

This week, Iranian Energy Minister Hamid Chitchian hosted Russian Energy Minister Alexander Novak for a two-day summit concluding in Tehran. Russian officials during the summit said energy is an "instrumental" part of the bilateral relationship with Iran.

Iran and Russia are both targets of U.S. economic sanctions. Harf said if any formal deals emerge from bilateral meetings, "we will act."

The Kremlin said sanctions would have no impact on bilateral affairs with Tehran.