"I regret the decision of the American president. I think it's a mistake and that's why we Europeans have decided to remain in the nuclear agreement of 2015," he told German national broadcasters ARD and Deutsche Welle, according to remarks released by the French presidency.

"I had the chance to tell President (Hassan) Rouhani that just now," he said, referring to a phone call earlier with the Iranian leader.

The French president stressed the importance for the European powers to reaffirm their commitment to the deal.

"The Europeans' decision allows us to prevent Iran from immediately restarting their (nuclear) activities and to avoid escalating tensions," he said.

"What's most important is to maintain stability and peace in the Near and Middle East," he stressed.