The US has announced that international firms have six months to halt existing business and cannot enter into new contracts or face crippling fines.
Le Maire said that Europe should resist the US becoming the "economic gendarme of the planet".
But what can Europe do to protect itself from this American domination?
Nothing, according to lawyer and Middle East specialist Ardavan Amir-Aslani.
“They are taking about reinstating EU blocking regulations, which were used in 1996 as a countermeasure against US sanctions targeting countries doing business with Cuba," he told RFI. "But all this would do would be to provide an excuse for a European entity who does business with Iran in non-compliance with US sanctions. It will not stand up in any court, it is a false hope.
"When America says no, it means no. And that is the tragedy that the Iranian government must confront."
Lack of transparency
The reality of doing business with Iran has never been simple and the original sanction relief in 2015 did surprisingly little to help this.
There is very little transparency in Iran's business systems and that is obviously a disincentive to international trade.
“A lot of the US sanctions actually remained in place after 2015, including a block on any access to the US dollar and any access to the US financial system, this is the key element that has stopped trade with Iran,” says Ali Ansari, a professor of Iranian History in St Andrews University.
The US position remained very ambiguous after the 2015 decision to remove certain sanctions.
Unilateral action targets potential trading partners
But this week's unilateral American action is essentially intended to warn off other nations from trading with Iran. Trump does not want to trade with Iran and he does not want anyone else to, either.
“When the US goes after you, the risk is a devastating fine," says Manuel Lafont Rapnouil, head of the European Council of Foreign Relations. "Everyone remembers the very severe fine that was imposed on BNP Paribas for its activities in Sudan. Countries will realise that the importance of their financial relationship with the US outweighs any other such relationship and they will not be willing to risk this."
In the immediate future, Iran's Foreign Affairs Minister Javad Zarif will meet his British, French and German counterparts in Brussels on Tuesday to discuss Trump's withdrawal from the nuclear deal and its ramifications.
The EU has said it is determined to work with Russia and China, who also signed the accord, to keep it alive.
The question is who, if anyone, will benefit from this decision to restore sanctions.
It is unlikely to be the Europeans or, indeed, the Iranians.
Economic experts say it is most likely to be Russia.