Iran's foreign minister defended Tuesday what he said was a "balanced" nuclear deal with world powers, telling lawmakers there was a need to accept that the negotiations had required compromise.

In a speech to parliament, Mohammad Javad Zarif emphasised that last week's agreement would secure the lifting in coming months of UN and Western sanctions imposed on Iran over its nuclear programme.

In return, Iran has agreed to put curbs on its atomic activities for at least a decade but it will continue to enrich uranium and be allowed to pursue research and development of more modern nuclear technology.

The deal and restrictions, including a more rigorous inspection regime, aim to remove Western concerns that Iran is seeking an atomic bomb -- an allegation it has always denied.

Zarif, who led Iran's negotiating team, was feted in street celebrations in Tehran after the deal was announced last Tuesday, but members of the conservative-dominated parliament have proved a tougher sell.

In a sign of their scepticism, just days before the final negotiations started in Vienna, lawmakers passed a new law which they said was to defend the nuclear programme, but which the government opposed.

Some hardliners in parliament have railed against the diplomacy, arguing that too many concessions were made.

- 'Give and take' -

But Zarif said that the long-running talks could never have satisfied Iran's or the West's every demand.

"We should not forget that any deal is a give and take and each side gives up part of its demands to realise the more important part until what has been given and received is balanced," he said.

"Iran's key objectives on which we insisted are what we gained. For the other side the key demands were to prevent Iran from reaching nuclear weapons through limitations and supervision."

Suggesting that Iran got the better side of a bargain with the West, and reiterating Tehran had never sought nuclear weapons, Zarif added: "What they gained was a vain effort to get what was already acquired.

"Our biggest achievement is the stamp by the UN Security Council confirming (uranium) enrichment in Iran."

However, in a move that could possibly delay parliament's approval of the deal, lawmakers voted to appoint a 15-member committee to evaluate the text of the Vienna agreement. Its members are yet to be selected.

US lawmakers in Congress have 60 days to review the deal.

The UN Security Council unanimously adopted a resolution on Monday endorsing the historic deal, clearing the path to remove the sanctions that have crippled Iran's economy in recent years.

It marks formal UN approval for the hard-won agreement reached between Iran and the five permanent members of the Security Council plus Germany.

Although Iran's parliament has the right to reject the agreement, it is unlikely to do so as the country's supreme leader Ayatollah Ali Khamenei has signalled his approval of the government and its negotiators' actions.

And on Tuesday, Ali Akbar Velayati, Khamenei's foreign affairs adviser, added his personal backing.

"If there is something that hasn't been achieved, definitely they could not have done more," Velayati said of Zarif and his colleagues in the talks.

"Through all my years of experience I do not know a stronger diplomatic team."