"Linking implementation of this mechanism... with the requirements of institutions such as the FATF is unacceptable," the foreign ministry said, referring to the international Financial Action Task Force.

Iran is on an FATF blacklist drawn up to counter money laundering and the financing of terrorist groups, but the Paris-based organisation has suspended counter-measures since 2017 while Tehran works on reforms.

EU leaders on Monday welcomed the bloc's new mechanism to trade with Iran but warned Tehran over its ballistic missile programme and regional policies while calling for it to implement reforms to comply with FATF demands.

Britain, France and Germany created the system last week to allow firms to trade with Iran without falling foul of US sanctions.

The foreign ministry, in its statement, welcomed the EU's "positive stances" but also criticised the bloc's warnings on its missile programme and its regional policies.

"Iran's defence activities... are merely defensive, deterrent and a domestic matter that has never been on the agenda of our negotiations with other countries," it said.

"Raising such issues under current regional circumstances and clear threats against the national security of the Islamic Republic of Iran is not constructive," the ministry said.

It urged European countries "to take a realistic look at regional incidents and issues and not to be influenced" by the United States.

Brussels, for its part, hopes the special payment mechanism for trade with Iran -- registered under the name INSTEX -- will help save the 2015 nuclear deal between Tehran and major powers.

Washington has reimposed sanctions after President Donald Trump last year quit the accord which lifted the measures in exchange for curbs on Iran's nuclear programme.

Iran has welcomed INSTEX as a "first step", while US officials have said it would not affect its efforts to exert economic pressure on Tehran.