Saied's supporters, whose rally in central Tunis was smaller than recent opposition protests, said the president's opponents were corrupt and called for opposition parties to be banned.
"Our message is clear: we ask Saied to arrest the corrupt ... the future is not for parties," said Ahmed Hammami, who organised Sunday's demonstration, where the president's supporters chanted: "Traitors should be accountable."
Saied and his committee planning to draft a new constitution
Saied, who seized executive power last year before saying he would rule by decree and dismissing the parliament, is forming a committee to draft a new constitution that he intends to put to a referendum in the summer.
His consolidation of power has accelerated in recent weeks. He has taken control of the previously independent judiciary and electoral commission and threatened to restrict civil society groups, giving the 64-year-old almost total control.
The crisis has endangered democratic gains since 2011, when Tunisians toppled long time autocrat Zine al-Abidine Ben Ali, sparking a wave of revolts against authoritarian leaders across the Arab world.
Saied has said his actions were needed to save Tunisia from years of economic stagnation and political paralysis at the hands of a corrupt, self-serving elite.
Frustrated by years of turmoil, a large majority of Tunisians appeared to back Saied's moves last summer but a growing economic crisis risks undercutting his popularity.
Saied rejects broader talks
Saied has said dialogue over Tunisia's political system will be limited to his supporters, rejecting calls by main parties, the powerful labour union and foreign donors for broader talks.
There has been no major crackdown on the opposition or free speech, but Saied has been increasingly outspoken against his opponents.