Tunisia's Radio Mosaique said its broadcasters Haythem El Mekki and Elyess Gharbi are being questioned by police on Friday in an investigation linked to journalistic content.
El Mekki, who presents a daily show on Radio Mosaique criticising Saied's policies, this week raised concerns about the country's methods of recruiting police after a National Guard member killed two visitors and three policemen in a bloody attack on a Jewish synagogue this month.
The government has cracked down on prominent opposition leaders and critics this year, including arresting the head of Radio Mosaique, Nourredine Boutar, in moves that have angered Western countries and human rights organizations.
Activists and journalists say freedom of speech faces a serious threat under Saied's rule.
Dozens of journalists and activists protested on Thursday against restrictions of freedoms and trials targeting journalists and bloggers.
"These are dark times. Freedom of speech is increasingly hit. About 20 journalists and bloggers are being pursued because of posts or positions against authorities," journalists' union chief Mahdi Jlassi told Reuters.
Freedom of speech and media were key gains for Tunisians after the 2011 revolution that ousted autocratic President Zine El Abidine Ben Ali and triggered the Arab Spring protests.
But President Kais Saied has systematically moved to curb speech and other freedoms.