Kais Saied, a political outsider and retired law professor, was sworn in as Tunisian president on Wednesday after he won a landslide victory in this month's election.
"There will be no tolerance in wasting any millime (cent) of the money of our people," Saied said in a speech.
He vowed to protect freedoms, saying: "Those who have nostalgia to go back to the old years only pursue illusions and mirages," he added.
Tunisia’s president controls foreign and defence policy, governing alongside a prime minister chosen by parliament who has authority over domestic affairs.
But Saied said he envisaged a bigger state role in the economy.
"We are moving from frustration to construction and work," he added.