The suspect had gone to the southwestern city of Carcassone “with a view to carrying out a violent act, in particular targeting Americans and Russians,” a judicial source said.
A source close to the investigation said the suspect was arrested in possession of a knife and a small mallet.
A source close to the investigation also confirmed the man was suspected of planning an attack on tourists, reported the AFP news agency.
The suspect comes from the southern French town of Lunel — notorious for the number of residents who have left to wage jihad in Syria — but has been living in the nearby Tarn region.
The man was arrested on Monday night, according to the La Dépêche du Midi newspaper.
The paper reported that the man had connections to the Islamic state and had been radicalized online.
It reported that he was also looking to target British tourists, then to turn his attention on security forces.
A medieval walled city and UNESCO World Heritage site, Carcassone is one of France's biggest tourist attractions with its drawbridges, watchtowers and cobbled streets.
News of the arrest comes just one day after Belgian police were warned that a fresh wave of Islamic State jihadists had left Syria and could commit attacks imminently in France and Belgium, according to media reports.
“Fighters travelling without passports left Syria about a week and a half ago in order to reach Europe by boat via Turkey and Greece,” a memo sent to police and security services across Belgium said, according to La Derniere Heure newspaper.