Acrimony between the European establishment and Mr. Trump mounted for months around his accusations that North Atlantic Treaty Organisation is "obsolete", his openness to working with Russian President Vladimir Putin, his criticism of the Iranian nuclear deal, his skepticism about an U.S. -EU free trade deal and his outspoken admiration for anti-EU nationalist politicians such as Britain's Nigel Farage.
"I was reassured by what I heard in the meetings on the intention to stick to the full implementation of the agreement", Mogherini said during a briefing for reporters.
Trump has expressed openness to working more closely with Russian Federation, a stance that has rattled European allies and drawn criticism from Democrats and Republicans who say Russian Federation is an adversary of the United States and other Western democracies.
The European Union acted as the coordinator for the negotiations in the lead-up to the JCPOA.
While in Washington, Mogherini had talks with senior members of the Trump administration, including Trump's son-in-law Jared Kushner and Secretary of State Rex Tillerson.
Mogherini said the new administration had not decided on a new USA ambassador to the European Union yet.
Iran was Mogherini's priority on this visit, she said, but she also came to draw some clear lines for the new administration.
Mogherini said this during her visit to Washington on Friday, an Ukrinform correspondent reports.
"The deal is working" and needs to remain intact, Mogherini said. The State Department provided no summary of his meeting with Mogherini afterward, as has been common practice for both Democratic and Republican administrations.
"That has to be taken into consideration", she stressed.
But she made clear that the European Union would not isolate Tehran.
She says she raised concerns about the man rumored to become the next USA ambassador to the EU, Ted Malloch, another supporter of Brexit and someone who has suggested the European Union "needs a little taming".
"No one tells us what to choose", Mogherini said.
The situation grew particularly biting last month, when Mr. Trump charged that German Chancellor Angela Merkel's open-door immigration policies were an invitation to terrorists and a "catastrophe" - an assertion that was followed by the president's executive order to block refugees from the USA and ban visas for seven Muslim-majority nations.
German Chancellor Angela Merkel, Europe's most powerful leader, told other European leaders last week that the continent must stand on its own during Trump's tenure.