Addressing a UN conference to review the 1970 Non-proliferation Treaty (NPT), the Iranian Foreign Minister Kamal Kharrazi on Tuesday also accused Washington of endangering world peace.
"Iran is determined to pursue all legal areas of nuclear technology including uranium enrichment, exclusively for peaceful purposes," Kharrazi said.
He said it was wrong to limit "access to peaceful nuclear technology to an exclusive club of technologically advanced states under the pretext of non-proliferation".
He attacked the United States for not scrapping its own arsenal as required by the NPT.
The US says uranium processing
plants in Iran are not needed
"Unilateral nuclear disarmament measures should be pursued vigorously," Kharrazi said. It was also "abhorrent that ... the dangerous doctrine of the use of nuclear weapons against non-nuclear states and threats was officially proclaimed by the United States and Nato".
Kharrazi also attacked Israel, saying its assumed nuclear arsenal "has endangered regional and global peace and security".
"Israel has continuously rejected the calls by the international community ... to accede to the NPT," he said.
Israel, which neither admits nor denies having the bomb, is estimated to have around 200 warheads.
Rising tensions about Iran as well as North Korea, which has said it has nuclear arms, dominated the opening of the month-long UN-sponsored conference on the NPT.
The United States on Monday pressed the 188 attending nations to ensure Tehran and Pyongyang are denied peaceful nuclear energy benefits because they had violated the treaty.
In Washington, US State Department spokesman Richard Boucher said there was no reason for Iran to have an enrichment and plutonium reprocessing programme.
"The only way to really ... reassure the world that they are not going to be a nuclear threat is to eliminate those programmes," he said.