EU circles the wagons around Iran deal

During the press conference Mogherini also announced she will travel to Washington early next month to bolster support for the accord.

Over the past weeks Trump has repeatedly criticised the deal signed by his predecessor Barack Obama, and on Friday refused to admit that Iran is complying with the agreement during a speech at the White House - stating that "multiple violations of the deal came from Tehran" and threatening to re-impose sanctions against the country.

"The issue with the Iran agreement is it does not achieve the objective," US secretary of state Rex Tillerson told CNN on Sunday.

"We're going to work with our European partners and allies to see if we can't address these concerns, which are concerns of all of us," he added.

In Luxembourg, Mogherini made clear that the International Atomic Energy Agency "has verified eight times that Iran is implementing all its nuclear related commitments" following a "comprehensive and strict monitoring system."

With the 2015 agreement, Iran agreed to limit its nuclear programme in exchange of a relief from the long-standing sanctions.

The joint statement said that Trump's decision not to certify Iran's compliance with the JCPOA was something that happens in the "context of an internal US process."

The US is now deciding on the deal, with Congress having 60 days to decide whether re-impose nuclear sanctions on Iran or not. The decision would require a simple majority that could be reached by Republicans in the Senate.

In this respect, the EU hopes the US will consider the "implications for the security in the US, its partners and the region" before taking further steps, the statement said.