Iran needs no one's permission to build missiles: Rouhani

"The strengthening of the capability of the Iranian armed forces ... is only for defending the country and we will ask no one's permission to build up the armed forces, and to build missiles and aircraft," he said at a televised event showcasing some locally built military hardware, according to Reuters.

He said Iran had never had "aggressive aims, but peace is not a one-way road and if we decide to be peaceful the other party ... may not. So there is a need for vigilance".

Rouhani's statement came as an apparently defiant response to US efforts to hamper the Iranian military ahead of an election in May, where he hopes to secure a second four-year term.

The 68-year-old cleric, who has won praise since his landslide win in 2013 for taming inflation and reaching a groundbreaking nuclear deal with world powers that ended many sanctions, has had to defend himself from critics who claim he had been duped by the West, a charge bolstered by fresh sanctions coming from Washington under US President Donald Trump.

"The preservation of the (nuclear deal) is one of the most important political and economic issues in the Iranian nation," he said on Friday as he registered to run for re-election.

Trump has criticised the nuclear deal and pledged during his election campaign to stop Iran's missile programme.

In January, after Iran test-fired a new ballistic missile, Trump tweeted that it was "playing with fire".

A bill to impose new sanctions on Iran over ballistic missile launches and other non-nuclear activities has been delayed in the US Senate due to concerns about the presidential election.

Iran has long boasted of having missiles that can travel 2,000 kilometres, placing much of the Middle East, including US-backed Israel, in range.