Irans decision to carry out enrichment for research is irreversible, Foreign Ministry spokesman Hamid-Reza Asefi told reporters at his weekly press conference.
Asefi said that Tehran hoped that a deal could be reached over industrial-scale uranium enrichment but that it was not willing to give such a right.
He denied reports that Tehran had run into difficulties operating a cascade of 164 centrifuges to enrich uranium.
Asefi said that negotiations with the United States to resolve the issue were out of the question.
He said that sanctions against Tehran would be more damaging for countries which imposed them than for the Islamic Republic.