Iran's state-owned car manufacturer Iran Khodro unveils the Peugeot 207i, a locally built version of the French automobile firm's 207 model, in Tehran on Feb. 20, 2010. France's PSA said on June 4, 2018, that it would pull out of two joint ventures to sell its cars in Iran to avoid the risk of U.S. sanctions. (Atta Kenare/AFP/Getty Images/file)

France, Britain and Germany warned the Trump administration in a letter released Wednesday that “as close allies,” they expect the United States not to enforce secondary sanctions against their companies doing business with Iran.

“We strongly regret the decision” taken by the administration to withdraw from the Iran nuclear deal and to reimpose U.S. sanctions, the Europeans said. But, they said, they expect that the United States will “respect our political decision” to stay in the agreement themselves.

The letter, dated Monday and sent to Treasury Secretary Steven Mnuchin and Secretary of State Mike Pompeo, comes as Trump prepares to meet with leaders of the three European governments, along with Canada, Italy and Japan, at the Group of Seven summit on Friday.

All of those countries also face economic penalties under new tariffs Trump has imposed on steel and aluminum imports, and all have expressed various degrees of anger at the president.

Secondary sanctions, prohibiting U.S. entities from doing business with those in other countries who do business with Iran, were part of the pre-deal restrictions that were lifted with its implementation. Although they are not now in effect, the administration has indicated it is likely to reimpose them at some point before the end of this year.

Major European companies with Iranian contracts, including French energy giant Total and carmaker Peugeot, have already announced they are pulling out unless they receive an exemption from Washington to avoid problems with the United States and to retain access to its globally dominant financial system. American companies, initially allowed under the agreement to trade, finance and invest in Iran through foreign subsidiaries, are also preparing to leave.

A notice on the registration table of an international oil conference held Wednesday in London, S&P Global Platts, said that Iranians were barred from the event because of the organizer’s “fears of breaching the U.S.’s punitive measures,” the Financial Times reported.

Senior European officials have acknowledged that they are not optimistic about receiving such U.S. waivers, and that there is little in general they can do to thwart Trump’s intentions of returning to a pressure policy against Iran.

Trump announced last month that the United States was withdrawing from the Iran nuclear agreement, which came into force in January 2016 after years of negotiations between Iran and a six-nation group that included the United States, Britain, France, Germany, Russia and China.

Negotiated for two years by the Obama administration, the deal lifted certain U.S. and international sanctions in return for restrictions on the Iranian nuclear program.

Throughout his presidential campaign, Trump called it a “bad deal,” and his administration has charged — with support from Israel and Iran’s rivals in the Middle East — that it was ineffective in stemming Iran’s alleged intention to develop nuclear weapons.

Before Trump’s announcement, the European partners spent months trying to address his concerns, only to have their efforts dismissed as irrelevant.

The letter sent this week was signed by foreign and finance ministers from all three countries, along with European Union foreign policy chief Federica Mogherini.

“As allies, we expect that the United States will refrain from taking action to harm Europe’s security interests,” it said. As they remain committed to “strong efforts to continue sanctions relief to Iran” in compliance with the agreement — and international monitors have certified Iran has not violated the deal — “we therefore ask for your assurances that the US will not take actions that might undermine the ability to do this.”

The Europeans asked that E.U. companies that initiated or concluded contracts with Iran once the agreement went into effect be exempted from any U.S. sanctions; that key sectors — including pharmaceuticals, automotive, energy and aircraft — be given exemptions from any secondary sanctions; and that existing financing and banking channels also be exempt.

Those European companies that do choose to leave Iran, the letter said, should be allowed extended wind-down periods to properly conclude their business there.

“We are sure that, building on our steadfast cooperation, we will manage to find swift and efficient remedies to these urgent concerns,” it said.

Following a “constructive approach” from the United States, it said, “we are ready to continue working together with you on matters of shared concern.”