"He is a terrorist, without a doubt, linked to radical Islam in one way or another," Valls told the national France 2 television channel.
According to the broadcaster, the minister said there was no fault with the security forces in relation to the incident.
On Thursday night, a truck rammed into a large crowd that was celebrating Bastille Day in Nice. At least 84 people, including children, were killed and dozens of others were injured.
The driver was shot dead by police. According to identification documents found inside the truck, the driver was a 31-year-old male resident of Nice of Tunisian origin. It is unclear whether he had any accomplices.