Three key European powers on Sunday called for dialogue and an end to the escalation over Iran's nuclear programme, as tensions further intensified between Tehran and the US.

The statement by the leaders of Britain, France and Germany expressed concern that the 2015 deal over Iran's nuclear programme risked further unravelling but said it was up to Tehran to ensure the deal survived.

"We believe the time has come to act responsibly and seek a path to stop the escalation of tensions and resume dialogue," said the English-language version of the statement issued by the Elysee.

The statement was published after President Emmanuel Macron hosted German Chancellor Angela Merkel and senior British cabinet minister David Lidington at the annual Bastille Day parade in Paris. "The risks are such that it is necessary for all stakeholders to pause and consider the possible consequences of their actions," it added.

The three European powers were among the key players in the 2015 deal (known as the Joint Comprehensive Plan of Action or JCPOA) on Iran's nuclear program.

But US President Donald Trump in 2018 announced Washington was pulling out of the deal, to the dismay of its European allies.

Angered that its beleaguered economy is not receiving sanctions relief it believes was promised under the deal, Iran has intensified its sensitive uranium enrichment work, prompting stern warnings from Washington.

"From May 8 onwards we changed our strategy of patience to that of retaliation... whatever action the other side takes we will retaliate in kind," Iranian President Hassan Rouhani said Sunday during a visit to North-Khorasan Province in northeastern Iran.

"If they decrease then we too shall decrease our commitments [in the deal]... If they fully implement their commitments then we too shall fully implement ours," he added according to the official government website dolat.ir.