Following President Donald Trump's decision to pull out of the 2015 nuclear deal with Iran and reimpose sanctions, European governments are going "to do everything to protect the interests" of their companies, said the official, speaking on condition of anonymity.

French diplomats said Trump's decision, announced in a short address to the nation on Tuesday, was expected despite efforts by President Emmanuel Macron to sway the US leader.

"Of course this decision is a worry, there are tensions," a second official said.

"It will be difficult to maintain this agreement in these conditions but we will do everything to find a way to protect this multilateral framework."

At a press briefing, the diplomats countered criticism that Macron had been ineffective in lobbying Trump to respect the accord during a state visit to Washington at the end of April.

Despite both men boasting of their close relationship in public, Trump did not inform Macron of his choice beforehand, even during a phone call between the two men just hours before his announcement.

"It was our responsibility to do it (lobbying Trump to stay in the agreement)," the first French official said. "And we did it with full knowledge of the facts."

He added that Macron would continue to play a crucial role in trying to salvage the agreement -- which the EU, Russia and China say they want to keep -- and reduce tensions in the Middle East.

"He's the only leader who has the ability to talk to other leaders involved, even those that don't talk to each other," the official said.

"That's something, above all in this time of tensions, that is precious."