Iran's Supreme Leader Ayatollah Ali Khamenei said the US would not be able to bring Iran to its knees in a row over sensitive nuclear work the West suspects is aimed at making bombs.
Mr Khamenei also told the visiting head of the UN nuclear watchdog that Iran's nuclear file should be handled by the International Atomic Energy Agency not the UN Security Council, which has imposed two rounds of sanctions on Tehran.
IAEA head Mohamed ElBaradei met Mr Khamenei and President Mahmoud Ahmadinejad during a two day visit to Tehran to push for more cooperation in resolving questions about Iran's atomic activity, which the US fears will be used to make warheads.
His visit coincides with fresh Iranian-US tension over a naval incident in Gulf last Sunday.
It was not immediately clear what, if any, concrete results were achieved during Mr ElBaradei's first trip to Iran since 2006.
Meanwhile US President George W Bush is also visiting the Middle East this week to seek Arab support in reining in Iran and has repeated his assertion that Iran was a 'threat to world peace'.
Mr Khamenei was defiant in his meeting with Mr ElBaradei, 'America's problem with Iran is beyond the nuclear issue,' he said.
'Americans are mistaken by thinking that by pressuring Iran over the nuclear issue they can break Iran. By bringing this and other issues to the fore, they cannot bring the Iranian nation to its knees,' he said.
