But US clout in global trade and finance limits their scope for action.
What Happened: French oil and energy company Total announced that it may withdraw from the Iran South Pars 11 (SP11) energy project, following U.S. President Donald Trump's decision to pull out of the Iran nuclear deal, formally known as the Joint Comprehensive Plan of Action, Reuters reported May 16. Tehran had repeatedly hailed the project as a symbol of the nuclear accord's success.
Total's withdrawal would be a blow to President Hassan Rohani, who had hoped its prestigious project would make other worldwide businesses regain confidence in Iran and bring in investment.
"It's a bad sign. With that in mind it's a logical decision". Further, Total's United States assets include about $10 billion, posing a risk it is unwilling to take.
But Total's announcement and similar ones by German insurance giant Allianz and Danish tanker giant Maersk earlier this week illustrate the major obstacles they face trying to overcome renewed US sanctions on Iran.
The 28 European Union leaders meeting in Sofia were not expected to reach any quick conclusions on how to try to shield their economic cooperation with Iran.
Total called for a waiver that would stipulate the company's protection from "any secondary sanction as per U.S. legislation".
But their efforts are undermined by the global reach of the US financial system, the dominance of the USA dollar, and the value to most European companies of the vital markets they have cultivated in the United States.
Washington is re-imposing strict sanctions on Iran, which were lifted under the 2015 deal to curb the country's nuclear ambitions.
"But given the rhetoric we have seen from the USA, they seem very keen to ramp up the pressure on the administration in Iran", said Tuvey.
They tasked experts with coming up with measures for a meeting of their deputies in Vienna next week. "Oil companies are not going to be able to invest in the upstream sector, traders and purchasers of Iranian crude are going to have to find other sources, or seek an exemption from the US government to be able to continue buying".
"Total, together with the other partner Petrochina, executed the contract related to the South Pars 11 (SP11) project, in full compliance with United Nations resolutions and US, EU and French legislation applicable at the time", the statement said.
The French oil major was among the first big western companies to return to Iran after the country emerged from years of isolation linked with its nuclear programme.
Underlining the depth of trans-Atlantic discord, the chairman of European Union leaders Donald Tusk said Trump had "rid Europe of all illusions" by withdrawing from the Iran accord and driving trade disputes.
Iran has asked European leaders to provide "guarantees" that the economic benefits from the deal will continue to flow - something European Union foreign policy chief Federica Mogherini said would be hard to do on May 15.