The total number of arrests from the protests around Iran remains unclear.
An official in Arak, around 300 kilometers (190 miles) southwest of Tehran, says 80 people had been detained there overnight.
Police have so far taken a relatively soft approach to the unrest, and there has been no sign that the powerful Revolutionary Guards have yet been deployed.
Iranian authorities have blamed external forces for fomenting the protests, saying the majority of social media reports were emanating from regional rival Saudi Arabia or exile groups based in Europe.
President Hassan Rouhani has so far not made any statement since the protests started.