European diplomats have vowed to preserve the multinational nuclear deal with Iran, as the United States reimposes sanctions against the Middle Eastern country.

EU foreign policy chief Federica Mogherini said the remaining parties to the 2015 agreement will maintain "effective financial channels" with Iran and ensure its continued export of oil and gas.

Mogherini, along with the French, German and British foreign ministers, further stated preserving the nuclear deal with Iran is a matter of respecting international agreements and a matter of international security.