Saied this week brushed aside much of the 2014 constitution, giving himself power to rule by decree two months after he sacked the prime minister, suspended parliament and assumed executive authority.
"The people want the fall of the coup," they chanted in the centre of Tunis along Habib Bourguiba Avenue, a focal point of the demonstrations that ended the rule of former President Zine El Abidine Ben Ali on January 14, 2011.
The crisis has endangered the democratic gains that Tunisians won in a 2011 revolution that triggered the "Arab spring" protests and has also slowed efforts to tackle an urgent threat to public finances, worrying investors.
Saied has said his actions, which his opponents have called a coup, are needed to address a crisis of political paralysis, economic stagnation and a poor response to the coronavirus pandemic. He has promised to uphold rights and not become a dictator.