European Council President Donald Tusk criticised USA president Donald Trump for withdrawing from the Iran deal and imposing steel and aluminium tariffs on the EU, citing the "capricious assertiveness of the U.S. administration", Politico reports.
"It's Europe's economic sovereignty, and what we are demanding is that we are exempted without conditions or time limits", French President Emmanuel Macron said in Bulgaria, where European Union leaders have gathered for a summit with Balkans countries.
Mr Trump's decision to walk away from the landmark nuclear deal with Iran - to which the UK, France, Germany, Russia and China are co-signatories - is being linked by the European Union with the USA administration's refusal to exempt the bloc from steel and aluminium tariffs.
European Union leaders agreed on Wednesday to keep on looking into these issues, but their previous efforts have not convinced Trump.
"The EU will continue fighting for a rules-based worldwide system despite recent decisions on climate change, tariffs and Iran", the source said after the leaders met over dinner in Sofia.
Iran's Foreign Ministry announced that Tehran will never renegotiate the 2015 nuclear deal despite the USA pressure.
"Looking at latest decisions of [Trump] someone could even think: with friends like that who needs enemies", wrote Donald Tusk, president of the European Council.
The EU should also seek ways, together with other partners, to address very real concerns over Iran's ballistic missile program and its regional activities, Tusk said.
"We would stay calm here, there is no need for the meeting on Wednesday to take decisions on specific modalities of the mechanisms that are to shield the interests of European companies", the official said.
British Prime Minister Theresa May, German Chancellor Angela Merkel and French President Emmanuel Macron will "present their assessment of the situation" to their colleagues, he said. Tusk said he wanted Europe to "stick to our guns" and described Trump's justification of tariffs on the basis of national security as "absurd". "But frankly speaking, Europe should be grateful by President Trump".
"Despite all the difficulties we have these days, the transatlantic relations are and will remain of outstanding importance", Merkel told the German parliament.
An EU source said after the talks the leaders agreed to start "work to protect European companies negatively affected by the USA decision".
"The extra-territorial dimension of USA sanctions is unacceptable".
"The EU and United States are friends and partners".
Behind their message of unity and firmness, some member states seem open to tolerating limited quotas from the United States on metals imports while others want a harder line, diplomats said.
The US decision to move its embassy in Israel to the disputed city of Jerusalem and its response to the killing of 60 Palestinians at protests in Gaza on Monday has further alienated the US from its European allies, who have spoken out on Israel's actions.
The EU's top energy official, Commissioner Miguel Arias Canete, is heading to Iran on May 18-21 for talks on energy cooperation, a symbolic gesture from the EU that it wants to stay engaged despite the US withdrawal.