Washington previously imposed restrictions on Iranian Supreme Leader Ali Khamenei and "those closely affiliated with him". US President Donald Trump has said he is responsible for "the hostile conduct" of Tehran towards the United States.

Iranian President Hassan Rouhani has stated that the sanctions against Tehran show the US administration's "despair", calling the White House "mentally retarded". Rouhani stressed that the sanctions against the country's Supreme Leader Ayatollah Ali Khamenei are futile, because he has no assets abroad.

The statement comes after Iranian diplomats slammed US policy toward the Islamic Republic.

"Imposing useless sanctions on Iran's Supreme Leader [Ayatollah Ali Khamenei] and the commander of Iran's diplomacy [Foreign Minister Mohammad Javad Zarif] is the permanent closure of the path of diplomacy", Foreign Ministry spokesman Abbas Mousavi stated.

The US sanctions targeting top Iranian statesmen come after the downing of a US drone by the Islamic Revolutionary Guard Corps last week. According to Tehran, the UAV and P-8 Poseidon spy plane accompanying it had violated the country's border.

At the same time, the US insists that the aircraft were flying above neutral waters in the Strait of Hormuz.

Addressing the incident, Trump said that the US planned to retaliate with a military strike, claiming he had stopped the operation 10 minutes prior to its start in order to avoid disproportionate casualties.