"It is not a normal situation; the enemy imagines it wants to enter with power, with psychological warfare ... our caution should be proportionate to the events around us," Rafsanjani said in his Friday prayer sermon carried live on state radio.

"We need caution in this situation, being aware, more far-sighted and talking more carefully," he said, describing mounting international pressure on Iran to freeze controversial nuclear work as an "evil movement to intimidate our nation."

He said the United States would gain nothing by attacking Iran, amid speculation that arch-enemy Washington could be planning a strike on Iran's nuclear installations.

"I do not think they will reach any results even if they take any kind of measures. How much could they gain in Afghanistan and Iraq?" asked Rafsanjani, who is known as a pragmatic moderate cleric.

"We should take the psychological warfare to their home, which is not calm now, as the Congress opposes (US President George W.) Bush's plan to send more troops (to Iraq). It was not like that before," he said.

He advised Washington to learn from history, citing the massive US presence in the Iranian army and intelligence service before the 1979 Islamic revolution which could not prevent the fall of US-backed Shah's regime.

"What more could a government, which had so much in Iran then, want to gain?"

Rafsanjani's comments came days after Iranian President Mahmoud Ahmadinejad dismissed the possibility of an attack, saying Washington was "in no position to hurt" Iran.

Ahmadinejad has been under criticism from both conservatives and reformists for his handling of foreign and domestic policy, including Tehran's disputed nuclear drive.

The United States has been at the forefront of the campaign to stop Iran's nuclear programme, saying it could be a cover for efforts to build atomic weapons, a claim vehemently denied by Tehran.

Iran has insisted it will not be diverted from its right to nuclear technology, despite a UN Security Council resolution last month which imposed sanctions over Tehran's refusal to suspend uranium enrichment.

Washington says it wants a diplomatic solution to the nuclear standoff but has never ruled out a military option to stop Iran's nuclear drive.

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