Britain, France, Germany and the United States are considering imposing sanctions that go beyond existing U.N. measures against Tehran over its nuclear programme, a British diplomat said on Friday.
Western powers fear Iran wants to build a nuclear bomb, while Tehran says it seeks to master nuclear technology for electricity.
"Our stance would not change with sanctions or the threat of sanctions," the students news agency ISNA reported spokesman Gholamhossein Elham as saying.
"It is important that our country is ready to insist on its rights under any conditions."
Britain, China, France, Germany, Russia and the United States have led diplomatic efforts to persuade Iran to freeze uranium enrichment.
The United States and Britain said on Wednesday the six had agreed to consider more U.N. sanctions against Iran after Tehran failed to halt enrichment, but Russia said there was no firm deal.
Iran gave a noncommittal, one-page letter this week to the six powers containing no reply to their offer to refrain from seeking more U.N. penalties if Iran froze expansion of its nuclear work.
Tehran promised a "clear response" at an unspecified date.China and Russia have big commercial interests in the world's fourth-largest oil exporter and have watered down the three previous U.N. Security Council sanctions resolutions against Tehran.