France has been under a state of emergency since November 2015 and has seen a string of attacks on security forces who have been regularly targeted, particularly those guarding key tourist sites.
An 18-year-old with a history of psychological problems was arrested on Saturday at the Eiffel Tower after brandishing a knife.
He told investigators he wanted to kill a soldier, sources close to the case told AFP.
In February, a man armed with a machete attacked four soldiers on patrol at Paris's Louvre Museum, while in April another extremist shot and killed a policeman on the Champs Elysees.
In June, a 40-year-old Algeria doctorate student who had pledged allegiance to the Islamic State group attacked a policeman with a hammer outside Notre Dame cathedral.