State television showed parliament speaker Ali Larijani and Revolutionary Guards officers inspecting the Imad missile, which has a range of 1,700 kilometres and is at the centre of a dispute over the missile programme.
The United States considered -- and then shelved -- imposing new sanctions following two recent missile tests which a UN panel said broke past resolutions aimed at stopping Tehran from developing missiles capable of carrying a nuclear warhead.
If such measures, reportedly targeting companies and individuals in Iran, Hong Kong and the United Arab Emirates with alleged links to the missile programme, were imposed they could jeopardise a hard-won nuclear deal due to be finally implemented within weeks.
Larijani was quoted as saying parliament would support an enhanced missile programme in a future five-year plan for the country.
State media reported a test of the Imad on October 11 and also that month showed footage of an underground missile base for the first time.
Tehran has always denied seeking an atomic weapon and argues that its missiles have never been designed to, nor ever would, carry a nuclear bomb.
Iran's ballistic missiles were not within the remit of the nuclear talks which resulted in an accord last July when Tehran agreed to curbs on its atomic programme in exchange for a lifting of economic sanctions.
The accord is due to come into effect on "Implementation Day", expected later this month, or soon after, when UN monitors sign off that Iran has applied the agreed restrictions on its nuclear activities.