Protesters are also marking 12 years since the Arab Spring revolution erupted across the region.
The central Avenue Habib Bourguiba – the artery of the capital, Tunis, and a key site for the revolution – was crowded on Saturday with thousands of protesters waving Tunisian flags, amid chants of “people demand the fall of the regime”.
A heavy police presence remained outside the Interior Ministry building on the street along with water cannon.
Protesters had pushed past police and metal barricades to reach the avenue, defying initial efforts by the authorities to keep separate several parallel protests that had been called by different political parties and civil society organisations.
The protest comes after disastrous parliamentary elections last month in which just 11 percent of voters cast ballots. The elections are meant to replace and reshape a legislature that Saied dissolved in 2021.
The runoff will take place on January 29.
The protests also come as the country goes through a major economic crisis, with inflation and joblessness on the rise. Tunisians have been hit with soaring food prices and shortages of fuel and basic food items like sugar, vegetable oil and rice in recent months.
On January 14, 2011, then-President Zine el-Abidine Ben Ali was forced out of power, transforming the country into a budding democracy that inspired the Arab Spring.
Saied, who was elected in 2019, suspended the elected parliament and began to reshape the political system, but low turnout for December’s election of a new, mostly powerless, legislature revealed little public appetite for his changes.
In an apparent response to criticism, Saied on Friday paid a surprise visit to Avenue Habib Bourguiba and went through the capital’s historic district, the medina. He called for caution against “intruders and renegades” who could mix with protesters to provoke clashes.