Johnson warned Britain that siding with Brussels would have economic consequences | Pool photo by Stefan Rousseau/Getty Images US to London: ‘Back us on Iran’ America’s envoy to UK warns of ‘serious consequences’ if British businesses pursue commercial interests in Iran.

America's top diplomat in London has urged Britain to support Washington's push to renegotiate the Iran nuclear deal and impose economic sanctions in the country, days after the EU vowed to stand by the agreement.

“America is turning up the pressure and we want the U.K. by our side,” Woody Johnson, the U.S. ambassador in London, said in an op-ed for the Telegraph published Sunday, calling on Britain “to use its considerable diplomatic power and influence and join us as we lead a concerted global effort towards a genuinely comprehensive agreement.”

U.S. President Donald Trump's decision to pull out of the Iran nuclear agreement — which he insisted is a “bad deal” that would not thwart Iran's nuclear ambitions — in May dealt a heavy blow to European allies, who vowed to stand by the deal, known as the Joint Comprehensive Plan of Action (JCPOA).

The U.S. call for British support comes days after EU leaders — including U.K. Foreign Secretary Jeremy Hunt, France's Jean-Yves Le Drian, Germany's Heiko Maas and EU top diplomat Federica Mogherini — issued a statement Monday making clear they are actively working to thwart renewed U.S. sanctions against Iran.

“We deeply regret the re-imposition of sanctions by the U.S., due to the latter’s withdrawal from the Joint Comprehensive Plan of Action,” they wrote, adding that the EU is taking legislative action — activating a so-called blocking statute — in a bid to protect EU businesses operating in Iran from the U.S. economic sanctions.

The first set of U.S. sanctions entered into force on Monday and targets sectors such as the car industry and aviation. A second set of sanctions covering Iran's oil exports will be imposed in November.

Johnson warned Britain that siding with Brussels would have economic consequences, saying: "Any businesses that put their commercial interests in Iran ahead of the global good will risks serious consequences for their trade with the U.S."

Trump's plea for British support on Iran has already been rebuffed by British officials, the Sunday Telegraph reported, citing continued U.K. support for the agreement.

Britain was among the negotiators of the original Iran deal in 2015, alongside France, Germany, China, Russia, the U.S. and the European Union.