Iranian nuclear chief Ali Akbar Salehi warned the head of the International Atomic Energy Agency (IAEA) against bias in a German media interview released Saturday, DPA reported.
"(IAEA chief Yukiya) Amano must take care that he does not lose his legitimacy by taking a political stance," Salehi told Spiegel news magazine.
Earlier this week, Salehi complained about the IAEA's most recent report, which criticized Iran's lack of cooperation with the agency's probe of the country's nuclear programme.
While Iran insists on its right to object to individual IAEA inspectors, the watchdog argues that the country is hampering the work of the international nuclear experts.
"If we refuse two inspectors, which is our right, (Amano) presents it as a lack of cooperation. We will not allow this tone of voice," Salehi said.
Iran's nuclear chief said his country was still prepared to cooperate with the IAEA, but wanted to issue a "friendly, but serious warning."
"Does Amano want to deliver an excuse for an attack on us?" Salehi asked. "Does Amano want a catastrophe?"
While many countries, including the US, are concerned about a possible secret Iranian nuclear weapons programme, Tehran's leaders say they have no such aims.
The article, which is to appear in Monday's edition of Spiegel, was released Saturday to German media.