TEHRAN, Young Journalists Club (YJC) - Interior Ministry spokesman Khlifa Chibani said Friday on Mosaique FM radio that 778 people have been arrested nationwide in the unrest, including 16 religious extremists.
He said Thursday night's protests were "limited," suggesting the situation was calming down.
But protest organizers called for new gatherings Friday.
European governments warned their citizens about potential rioting Friday and this weekend, when Tunisia marks seven years since the ouster of President Zine Ben Abidine Ben Ali.
The protests are prompting fears of a new political crisis in the country that inspired the 2011 Arab Spring uprisings.