President Joe Biden said he was "gravely concerned" about reports of the "intensifying violent crackdown on peaceful protesters".Mahsa Amini, a 22-year-old Kurdish woman, fell into a coma hours after being detained by morality police on 13 September in Tehran for allegedly breaking the strict law requiring women to cover their hair with a hijab, or headscarf.Women have led the protests that began after Ms Amini's funeral, waving their headscarves in the air or setting them on fire to chants of "Woman, life, freedom" and "Death to the dictator" - a reference to Ayatollah Khamenei.Iran Human Rights, a Norway-based group, has said at least 133 people have been killed by security forces so far.Ayatollah Khamenei's comments came a day after security forces violently cracked down on a protest by students at Iran's most prestigious science and engineering university, reportedly arresting dozens."