(CNN) -- The latest violent protests to hit Iran has prompted hundreds of arrests, including some prominent figures, and left at least eight dead, although the Iranian government denied its security forces have killed anyone.
Iran's Supreme National Security Council reported the eight deaths in a series of clashes over the weekend -- the deadliest since June protests followed the nation's disputed presidential election.
"For months, the Iranian people have sought nothing more than to exercise their universal rights," U.S. President Barack Obama told journalists during a break from his Christmas vacation in Hawaii. "Each time they have done so, they have been met with the iron fist of brutality, even on solemn occasions and holy days."
"It's about the Iranian people and their aspirations for justice and a better life for themselves," Obama said. "And the decision of Iran's leaders to govern through fear and tyranny will not succeed in making those aspirations go away."
In many cases, opposition media reported, government security forces prevented observances of Ashura, the major Shiite Muslim holy day marking the death of Imam Hussein, grandson of Prophet Mohammed, as a martyr.
Iranian opposition Web sites have kept up a steady stream of reports about the clashes, but official news agencies been largely silent. The Fars news agency ran three pages of photographs of peaceful mourning ceremonies marking Ashura, but there was no mention of protests.
But officials like Iran's Deputy Police Chief Ahmad Reza Radan and Tehran Police Chief Azizollah Rajabzadeh denied their forces had killed anyone. In fact, they told the semi-official Islamic Students News Agency, their forces fired no weapons and weren't even carrying firearms.
While the videos are dramatic and the news of deaths chilling, the roll call of arrestees grows longer and deeper into Iranian dissent.
As many as 500 people may have been arrested in Isfahan, the opposition JARAS news agency reported, among them Habib Nouri, the 50-year-old brother of Abdollah Nouri, the revolutionary-leader-cum-reformist-politician who served nearly five years in Evin prison for religious and political dissent.
Ayatollah Jaleleddin Taheri's son was arrested in Isfahan, another reformist Web site, javan-farda.com, reported. The Iranian government began applying pressure to Taheri, who is married to one of Ayatollah Ruhollah Khomeini's grandchildren, after he tried to lead a memorial service for Grand Ayatollah Hussein Ali Montazeri, the reformist cleric and key figure of the 1979 Iranian Revolution who died last week, the site said.
The government denied Taheri permission to hold a mourning ceremony for Imam Hussein at Isfahan's Grand Mosque, the Web site reported.
Also arrested were Ibrahim Yazdi, head of the Freedom Movement of Iran and former deputy prime minister after the Revolution, and Emad Baghi, founder of the Association for Defense of Prisoners Rights, the reformist Web site Parlemannews reported.
NoroozNews added the names of Ali Reza Beheshti Shirazi, son of the late Dr. Ayatollah Beheshti -- the founder of Iran's post-revolutionary judicial system -- and two advisers to former opposition presidential candidate Mir Hossein Mousavi, Mohamad Bagherian and Behzadian Nejad, to those who have been arrested.
Mousavi's nephew, Saeed Ali Mousavi, was reported among the dead Sunday.
Norooz also reported that government agents raided the offices of former reform President Mohammed Khatami's Baran Institute, arresting former cabinet minister Morteza Haji and Hassan Rassouli, who is the deputy director of the institute. Another raid nabbed Mousavi Tabrizi, the head of the clerical Association of Teachers and Researchers Qom, NoroozNews said.
And Nobel laureate Shirin Ebadi told CNN Monday that Iranian intelligence officials had detained her sister, dentistry professor Nushin Ebadi.