Iran said on Sunday that it is impervious to allegations by U.S. Secretary of State Condoleezza Rice, who accused Tehran's "unelected mullahs" of a "dismal human rights record" and of hiding efforts to build a nuclear bomb.
On Thursday, Rice made clear Washington that was unwilling to become involved in negotiations with Europe to broker a deal that would offer economic incentives to Iran if it agreed to halt its production of nuclear fuel.
"Such threats will have little effect on the Islamic Republic, and we will continue our path of sovereignty, independence and of saying no to hegemony," Foreign Ministry spokesman Hamid Reza Asefi told a news conference.
Iran denies Washington's allegations that it seeks nuclear warheads and argues that it only wants nuclear fuel to run power stations, such as the one it is building at its southern port of Bushehr.
Asefi also said that Rice's position would not sway talks with Britain, France and Germany.
"Negotiations have not reached a deadlock and still continue," he said.
But he added: "We think the Europeans must be more serious and show more dynamism."
Meanwhile, Iran's chief nuclear negotiator warned on Sunday that Iran would both retaliate and accelerate its drive to master nuclear technology if the United States or Israel attacked its atomic facilities.
Hassan Rohani, Secretary-General of Iran's Supreme National Security Council, also told Reuters there was nothing the West could offer Tehran that would persuade it to scrap its nuclear program, which Washington alleges may be used to make bombs.
Asked about a possible attack by the United States or Israel against Iran`s atomic facilities, Rohani said: "If such an attack takes place, then of course we will retaliate and we will definitely accelerate our activities to complete our (nuclear) fuel cycle."
Speaking in an interview, Rohani said Iran's ability to produce its own nuclear parts had made it invulnerable to attack, since it could simply rebuild whatever was destroyed.
"But I do not think the United States itself will take such a risk ... They know our capabilities for retaliating against such attacks," the cleric added.
Iran says its nuclear program will be used to generate electricity, not bombs. Washington alleges Tehran is using its civilian nuclear program as a front for weapons development.
The European Union, led by Britain, Germany and France, is trying to persuade Iran to turn a temporarily freeze of sensitive aspects of its nuclear work, like uranium enrichment, into a permanent cessation, in return for economic and political incentives.
Rohani said that even security guarantees or the removal of U.S. sanctions against Iran would not be enough to tempt Tehran into giving up its nuclear program.
"Uranium enrichment is Iran's right, based on Article 4 of the NPT (Nuclear Non-Proliferation Treaty) ... I do not think anyone in Iran would exchange or swap this right for anything else."