TEHRAN:  Iran's President Hassan Rouhani said Sunday that government bodies must provide "space for criticism" as he sought to head off days of unrest, but also warned protesters that violence was unacceptable.

Hundreds of protesters marched through Tehran and other cities in a fourth day of demonstrations as authorities cut access to social media.

Rouhani finally broke his silence on the protests that mark the biggest test for the regime since mass protests in 2009.