Iran will present "new initiatives" at nuclear talks with world powers in Istanbul at the weekend, the official leading the country's negotiating team, Saeed Jalili, said on Wednesday.
"The Iranian delegation will have new initiatives and we hope that the other party will have a constructive approach," he told Iran's Arab-language television Al-Alam, without elaborating.
Jalili, who is close to Iran's supreme leader Ayatollah Ali Khamenei, also warned the Western nations taking part not to try to add to coercive pressure on Iran.
"The language of threat and pressure has never yielded results and only reinforces the determination of the Iranian people," he said.
President Mahmoud Ahmadinejad echoed that statement in separate comments carried by the official news agency IRNA.
"The language of force and insults will give no result," he was quoted as saying.
"I say to them in the name of the Iranian people that the method you have adopted will have no result. They need to change their language and speak with respect."
Iran's lawmakers at the same time issued a statement backing Jalili's team, advising the world powers to accept "the undeniable reality" that Iran has a right to nuclear energy and urging "an end to the current trend" of sanctions.
The 204 MPs in the 290-seat parliament also underlined Iran's "opposition to nuclear weapons" as voiced by Khamenei.
Talks on Saturday in Istanbul are to bring together Iran and the so-called P5+1 group comprising the five permanent UN Security Council members (Britain, China, France, Russia and the United States) plus Germany.
They are seen as a crucial opportunity to lower international tensions in the standoff over Iran's nuclear programme.
The United States and its European allies suspect Iran's activities mask a drive to get to the "breakout" threshhold of having the capability to make atomic weapons.
They have imposed increasingly severe economic sanctions on the Islamic republic to pressure it to halt activities, notably uranium enrichment.
Iran denies any military dimension to its nuclear activities and has responded defiantly by accelerating them. It also asserts that the sanctions are having little effect and will never force it to make concessions.
In February, Khamenei said Iran considered nuclear weapons a "sin," echoing a 2005 fatwa he is said to have issued declaring the atomic bomb haram, or antithetical to Islam.
Sadeq Larijani, the head of Iran's justice system, said the West should know that Khamenei's word "is the greatest possible guarantee" because "all the institutions in the Islamic republic's regime serve under his orders," IRNA reported.
US Secretary of State Hillary Clinton referred to Khamenei's position during a trip to Turkey on April 1, saying the Iran/P5+1 talks will be aimed at how to "translate what is a stated belief into a plan of action."
"If the Iranians are truly committed to that statement of belief ... then they should be open to reassuring the international community that it’s not an abstract belief but it is a government policy," she added.
To that end, she said Iran should end enriching uranium to 20 percent and ship out its existing stocks, and open itself up to more intense inspections by the UN nuclear watchdog.