The new government will be formed "as soon as possible," he said — but did not give an exact date. He added that people "with the most integrity" would be chosen for the cabinet.
Saeid contends the "Tunisian people have rejected the constitution" and added that constitutions are not "eternal."
"Amendments must be made within the framework of the constitution," Saied told state-run broadcaster Wataniya and Sky News Arabia from central Tunis.
Earlier this week, An adviser to Saied told Reuters news agency that the president intended to suspend the constitution and suggest changes to the political system, which could be voted on via public referendum.
Saied's plans rejected by key trade union, opposition
The idea of amending or suspending the constitution has drawn broad criticism from Saied's opposition.
Tunisia's key workers' union, the UGTT, has called for new parliamentary elections rather than dissolving the constitution.
Saied froze the country's parliament on July 25, dismissed Prime Minister Hichem Mechichi and granted himself emergency powers.
Supporters of Saied say the moves were necessary to end the country's political stagnation, while critics say the president is engaging in a blatant power grab.
Rached Ghannouchi, the leader of the moderate Islamist Ennahda party, said suspending the constitution would cause Saied's government to lose "legitimacy."
Jailed opposition MP on hunger strike
Another critic, independent member of parliament Yassine Ayari, was arrested for speaking out against Saied's July 25 decision and calling it a "military coup." Ayari is now on hunger strike in a Tunisian prison, with family members worried about his health.
International leaders have also expressed alarm over Saeid's actions. On Friday, EU Foreign Affairs Representative Josep Borrell told Saied Europe was concerned "about the preservation of democratic gains in Tunisia."
Saied, a constitutional law professor, was elected in 2019 on a populist platform of fighting corruption and incorporating elements of direct democracy in the political system. His victory was viewed as a rebuke of the political elite, as he did not have any ties to the country's founding president, Habib Bourguiba.
Tunisia analyst Mariam Salehi speaks to DW
Man sets himself on fire in central Tunis
Earlier on Saturday, a man set himself on fire in downtown Tunis, according to media reports.
The 35-year-old doused himself with a flammable substance and then was rushed to the hospital, where he received treatment for third-degree burns, AFP news agency reported.
A similar act of self-immolation by fruit vendor Mohamed Bouazizi in 2010 was the catalyst for Tunisia's revolution against dictator Ben Ali the following year. The revolution in Tunisia led to similar uprisings in other Arab countries such as Egypt and Syria, in what became known as the Arab Spring.
In recent years, the Tunisian economy has struggled with a mix of high unemployment, inflation and skyrocketing national debt. The coronavirus pandemic has also burdened the country's hospitals this year, and the North African nation has struggled to procure enough life-saving oxygen and vaccines.