Iran's President Hassan Rouhani has met with Germany's top diplomat amid heightened tensions over the country's unravelling nuclear accord with world powers.

Rouhani met with Foreign Minister Heiko Maas just after a joint press conference between Iranian foreign minister Mohammad Javad Zarif and his German counterpart.

Maas's visit to Tehran is part of European efforts to save the historic 2015 nuclear deal with Iran, and ease heightened tensions with the United States.

The U.S. pulled out of the deal over a year ago, and recently has imposed heavy new sanctions on Iran. In May, Tehran said it would begin enriching uranium closer to weapons grade if Europe didn't come up with new terms for the deal by July 7.

The tensions between the long-time rivals recently soared when the U.S. deployed an aircraft carrier and B-52 bombers to the Persian Gulf.