Newly elected president Hassan Rowhani struck a diplomatic chord in his first news conference but offered little real change in key policy areas, especially on the long-running dispute over Iran's nuclear programme.

Concretely, he ruled out any halt to the nuclear activity that has drawn UN, EU and US sanctions, repeating a long-standing Iranian position and dashing hopes he might reimpose a moratorium on uranium enrichment adopted when he was chief nuclear negotiator.

Yet he did outline conditions for first-time direct nuclear talks with archfoe the United States in the hope of easing tensions that have led to Washington and Israel refusing to rule out military action over the programme.

And he refrained from any fiery or potentially confrontational rhetoric, maintaining his trademark composure and soft tone during the Monday's nearly two-hour press conference.

University professor and political analyst, Pirouz Mojtahedzadeh wrote in an op-ed piece in the conservative Tehran Emrooz daily that Iran's tone has softened with Rowhani, but that the policy remains the same.

"Styles change, and the discourse and the diplomacy will change, but this does not mean abandoning (fundamental) stances."

"Iran has shown good will by electing a moderate... Now the West should react positively," Mojtahedzadeh added.

The 64-year-old Rowhani said EU and US sanctions against Iran's oil and banking sectors, which have sent the economy into free fall, are unjust but promised transparent talks to try to resolve the underlying issues.

Iran will be "more transparent to show that its activities fall within the framework of international rules," he said, without elaborating.

"The idea is to engage in more active negotiations."

Iran has long been accused of dragging its feet in its talks with the so-called P5+1 -- the five permanent UN Security Council members and Germany.

Ten rounds of talks in 18 months between Iran and the International Atomic Energy Agency have produced no breakthrough.

The latest round, in Kazakhstan in April, ended with lead negotiator, EU foreign policy chief Catherine Ashton, saying the two sides remained "far apart" despite the P5+1 having sweetened an earlier offer.

Rowhani's press conference was widely covered in the Iranian media on Tuesday.

Vatan Emrooz, the hardline conservative daily, brandishing Rowhani's picture headlined: "The era of an enrichment halt is over."

Like-minded Jamejam headlined: "We will not abandon the Iranian people's legitimate rights."

They were referring to Rowhani's tenure as chief nuclear negotiator in 2003-2005, during the second term of reformist former president Mohammad Khatami, when Iran adopted a moratorium on enrichment.

Iran insists on international recognition of what it says is its "right" to enrich uranium, a key component of the nuclear fuel cycle that can also be used to make the explosive core of an atomic bomb.

And it has massively expanded its uranium enrichment facilities, extending the process to 20 percent and raising fears that the 90 percent required for a warhead is but a step away.

World powers say Tehran must end enrichment to high levels and verifiably suspend operations at the Fordo mountain bunker where such activity takes place before recognising Iran's rights to pursue less threatening activities.

Iran denies it is developing the atomic bomb and argues that it requires a nuclear programme solely for peaceful medical and energy needs.

Rowhani reiterated there could be no return to the moratorium on enrichment, saying "this period is over."

Khatami's successor, outgoing President Mahmoud Ahmadinejad resumed the enrichment programme, triggering successive UN Security Council ultimatums to suspend it, some of them backed up with sanctions.

The unilateral EU and US sanctions followed.

Ashton said she would take Rowhani up on his promise of more constructive engagement.

"I will continue to do my work to urge Iran to work closely with me... to build confidence in the nature of their nuclear programme," she said.

Mohammad Saleh Sedghian, head of the Tehran-based Arabic Centre for Iranian Studies, told AFP the success of "every domestic and foreign and political process depends on its discourse... the discourse can change political equations."

The "speech was filled with hope and ambition," he added.

Rowhani expressed readiness for bilateral talks with Washington to allay its concerns that Tehran's nuclear programme is cover for a drive for a weapons capability, but not without conditions.

"The US should not interfere in our internal affairs, recognise the rights of Iran including nuclear rights and stop its unilateral policies and pressure," he said.

"The next government will not give up the legitimate rights of the country," Rowhani added.

That prompted a headline from the oft-banned reformist Shargh newspaper, which read: "Rowhani's three conditions of negotiations with the US."

US President Barack Obama has reacted cautiously to Rowhani's election, saying it showed Iranians wanted to back away from confrontation with the outside world but ruling out for the moment lifting economic sanctions on Tehran.

"Well, I think it says that the Iranian people want to move in a different direction," Obama told PBS television's "Charlie Rose" show.

Now, Sedghian said, the "ball is in the other side's court."

"Foreign and domestic players must seize the opportunity Rowhani's positive attitude offers, to turn it into action... The time for those who want to interact with Iran's new discourse has begun."