TEHRAN, Sept. 11 (UPI) -- Iran's supreme leader, Ayatollah Ali Khamenei, said Friday opposition leaders in Iran will face harsh scrutiny if they fail to follow Islamic Republic rules.

During an appearance at Tehran University Friday, Khamenei said opposition heads would face repercussions if they called for protests or made vote-rigging allegations in regard to Iran's presidential election in June, the Los Angeles Times reported.

"The system will not take action against anyone as long as they perform within the framework of the system, do not resort to violence, do not disturb the calm in society and do not carry out unlawful actions such as spreading lies and rumors," Khamenei said.

The Times said the Iranian leader also spoke of international pressure against Iran in relation to the country's controversial nuclear program.

"Whether in the nuclear or non-nuclear fields, day by day, under international pressure the Islamic Republic of Iran stands fast," Khamenei said. "Those who say we have to lay down our guns against enemies are making a mistake."