According to the BFMTV broadcaster, the man was detained on Monday evening.
The man was remanded in custody at the request of the prosecutor's office, the broadcaster said.
On December 11, an attacker opened fire close to the Christmas market.
The gunman was identified by police as a local resident named Cherif Chekatt, 29, who was known to the law enforcement for previous multiple offenses. Later, the French interior minister confirmed that the suspected shooter had been killed by police. According to the latest media reports, the attack left five people killed and 11 others injured.