"The UK has a clear position on the Iran nuclear deal: we regard it as a crucial agreement that makes the world a safer place by neutralizing the threat of a nuclear-armed Iran", the British Foreign Office said.
"The American administration has failed to undermine the nuclear deal".
The Foreign Ministers of Britain, France and Germany threw their weight behind the pact limiting Iran's nuclear ambitions and insisted that the Islamic Republic is respecting it.
With the announcement Friday, Trump also said the Treasury Department is sanctioning 14 more Iranian individuals and entities.
Chinese Foreign Minister Wang Yi told Iranian Foreign Minister Mohammad Javad Zarif by phone that implementation of the deal had not been "derailed" but would face "some new complicating factors", the state news agency Xinhua reported. Trump wants them to help the USA devise a new agreement created to prevent Iran from escalating nuclear activity again next decade, as permitted under the 2015 arrangement reached by President Barack Obama. Trump is also waiving other US penalties covered by the agreement, including on Iran's oil and gas sectors, which were up for renewal next week.
While there may be some relief that Trump has yet to torpedo the hard-won accord, there were clear signs of frustration from European capitals in the runup to the decision.
Trump stopped short for a third time of re-imposing harsh sanctions meant to push Tehran to give up its nuclear weapons research.
On Friday, the White House said that Trump would waive sanctions against Iran to keep the deal alive, but it would be the "last time" unless the United States and Europe reach an agreement in the next 120 days to strengthen the landmark agreement. Washington also imposed sanctions on the head of Iran's judiciary and others.
"And if at any time I judge that such an agreement is not within reach, I will withdraw from the deal immediately".
Trump is required to renew the existing deal every 120 days under U.S. law.
Under the deal, Iran agreed to curb its nuclear programme, in exchange for lifting of most sanctions.
United Nations inspectors have certified Iran's compliance with the deal nine times, most recently in November.