Iran's supreme leader issued a stern warning to members of the opposition on Friday — threatening to respond with force to those who drew their "swords" against the clerical ruling establishment.

The message from Ayatollah Ali Khamenei came during Friday prayers, and was a warning that Iran's government would not tolerate dissent.

It was the first time Khamenei led Friday prayers since June, when he endorsed President Mahmoud Ahmadinejad's re-election, blamed the opposition for widespread bloodshed throughout Iran, and accused Western powers of medlding in the country's internal affairs.

"Resisting the system and taking out the sword against the system will be followed by a harsh response," Khamenei is quoted by Reuters as telling worshippers in a sermon broadcast live on state television.

"If somebody stands against the basis of the (Islamic) system and violates people's security, the system is forced to stand against it," Khamenei said.

Khamenei did not address proposals made by Tehran on Wednesday geared toward cooperating with world powers, but he reiterated that the Islamic state should not back down from what he called its own "nuclear rights."

"It is a sign of deviation to give up one's rights, nuclear rights or non-nuclear rights, instead of insisting on them," he is quoted by Reuters.