Moderate president-elect Hassan Rowhani vowed on Saturday to apply "constructive interaction" with world powers to ease tensions raised by Iran's nuclear ambitions and its support for the embattled Syrian regime.

"Moderation in foreign policy means neither surrender nor confrontation but constructive and efficacious interaction with the world," Rowhani said in his first live televised remarks since his election on 14 June.

Iran is at odds with world powers over its controversial nuclear ambitions, which the West and Israel suspect have military objectives, and its support for Syria's President Bashar al-Assad.

Rowhani, who thrashed his conservative opponents by winning almost 51 percent of votes to succeed Mahmoud Ahmadinejad, did not mention either issue directly.

But he did say he would move to ease tensions after he formally takes office on 3 August.

Under his administration, "interaction and dialogue will be based on reciprocity, respect and mutual interest, and seeking mutual detente," Rowhani said.

His tone contrasted with eight years under Ahmadinejad marked by fiery, contentious remarks on a wide range of international issues, including the nuclear drive, Israel's right to exist and the Holocaust.

Ahmadinejad, whose disputed 2009 re-election plunged Iran into domestic turmoil, has also drawn the ire of domestic foes for a populist economic agenda, and what his critics call mismanagement of vast oil wealth.

On Saturday, Rowhani pledged "moderation" in which "a balance must be achieved between realism and idealism".

He also vowed to fight for "all of Iran's rights and the nation's demands", but without elaborating.

Rowhani campaigned on promises of engagement with the West to resolve the nuclear stand-off and lift sanctions, which have cost the economy billions in vital oil revenues and foreign investment, leaving the country struggling with raging inflation, high unemployment and a depreciated currency.

Iran insists its nuclear activities are aimed at civilian applications, under which it has the right to enrich uranium, whose highly enriched form can be used as the fissile core of an atomic bomb.

Rowhani, a 64-year-old mid-ranking cleric, headed a relatively moderate nuclear negotiating team under reformist president Mohammad Khatami in the early 2000s, when Tehran agreed to suspend its enrichment activity.

But that programme, in which final decisions rest with supreme leader Ayatollah Ali Khamenei, resumed two years later when Ahmadinejad was first elected.

Iran has since then massively expanded its facilities for the enrichment of uranium, extending the process to 20 percent, an operation under the supervision of the UN nuclear watchdog.

Rowhani is considered a regime insider as he has held senior political posts since the inception of the Islamic republic, including being Khamenei's representative in the top security council since 1989.

He also enjoys the widespread support of reformists and moderates, in particular pragmatic two-time ex-president Akbar Hashemi Rafsanjani.

Rowhani's election has created a surge of hope among the population that there will be change, including the easing of restrictions at home.

In his address on Saturday, Rowhani urged the authorities to be more tolerant over civil freedoms.

"Joy and exhilaration is the people's right," he said of two nights of street parties, one after the announcement of his election and another after Iran's June 18 qualification for the 2014 World Cup in Brazil.

He thanked the police for allowing the festivities that ran past midnight, but said: "Don't impose too many restrictions. Our people are moralistic and aware of the Islamic, political and ethical boundaries."

"The people's dignity must be preserved," he added.