United Nations: Iran has approached the United Nations over the latest sanctions imposed on it by the US government, calling the measures "extremely dangerous" and aiming to harm civilians.

Iran's UN Ambassador Mohammad Khazaei said in a letter to UN Secretary-General Ban Ki-moon that "continuation of this awkward US policy is extremely dangerous and will never serve to the maintenance of international peace and security."

The protest was made a day after the US government banned dealings with the national airline Iran Air and a port operator owned by Iran's Revolutionary Guard. Both were accused of involvement in banned weapons and technology transfers helping Iran's nuclear programme.

Iran faces four rounds of UN sanctions over its refusal to halt uranium enrichment. The country, however, denies Western allegations that it is trying to build a nuclear bomb.

The US government "has sought recourse to a set of untrue and void allegations against my country in order to justify its unfair treatment towards the Iranian people," the ambassador said in the letter, part of which was released by the Iranian mission.

"There is no doubt that the main purpose of such an unrealistic and hostile policy is to affect the lives of the entire Iranian population and breach international law on harming civilians populations," Khazaei said.