Ayatollah Ali Khamenei, the Supreme Leader of Iran, says the country will continue developing nuclear technology.
The Ayatollah says Iran will press ahead with "full confidence"
"Our policy is clear, progress with clear logic and insisting on the nation's right without any retreat," state television quoted him as saying.
His comments come as the United Nations discusses its response to North Korea's claimed nuclear test on Monday.
Iran has always maintained the technology is for peaceful purposes and not for atomic weapons.
Last week, at talks in London, the six major powers trying to persuade Iran to curtail its nuclear research agreed to consult on the possibility of imposing sanctions.
The Ayatollah's comments are his first public remarks since the meeting.
He was also quoted as saying that while Iran had previously suspended its enrichment program, it would not do so again.
"Now with steady heart and full confidence we press ahead and nobody can give a good reason that the nuclear path is wrong for the country," he said.
Iranian President Mahmoud Ahmadinejad was also quoted by state television, saying the country would continue to negotiate and cooperate in the nuclear energy field.
Iran says their nuclear intentions are peaceful
"Iran's proposal is an appropriate framework for cooperation in the nuclear issue and the Iranian nation will continue the path of dignity with perseverance and prudence without any fear."
Tehran had rejected a 31 August deadline set by the UN Security Council that it suspend enrichment or face possible sanctions.
At the London talks last week, the US and the UK favoured immediate punitive sanctions, but China and Russia both said diplomacy was still the best way to achieve a solution.