Iran's defence minister has said he is "certain" the UN Security Council will not take any action over its ballistic missile tests despite calls from Western powers.

Britain, France, Germany and the United States wrote a joint letter on Monday calling for action over tests they said violated last year's landmark nuclear deal between Iran and major powers, and the Security Council resolution that enshrines it.

They said the two kinds of missiles fired by Iran on March 8 and 9, the Shahab-3 and Qiam-1, were a breach of the resolution because they were "inherently capable of delivering nuclear warheads," something Iran denies.

"I am certain that the Security Council and the United Nations will not respond as our actions are neither a breach of the Joint Comprehensive Plan of Action (the July nuclear deal) nor are they against Resolution 2231," General Hossein Dehghan said.

He reiterated Iran's longstanding denial that it ever had any ambition to develop a nuclear weapon and said its missiles were designed to carry only conventional warheads.

Diplomats at the United Nations said the Security Council is expected to meet on Friday to consider the alleged breach of Resolution 2231.

But they said action is unlikely as veto-wielding permanent member Russia is opposed to any new sanctions against Iran.

Last Thursday, Washington imposed unilateral sanctions over this month's tests adding several units involved in Iran's missile programme to its blacklist.

The Treasury placed sanctions on Shahid Nuri Industries and Shahid Movahed Industries, both units of the Shahid Hemmat Industrial Group Washington says is responsible for production of Iran's liquid-fuelled ballistic missiles.

It also sanctioned the Al-Ghadir Missile Command of Iran's powerful Revolutionary Guards, which it said appears to have operational control of the missiles.