The statement did not name the attacker, and the language implied that he may have acted independently.
The Islamic State group claimed Saturday that the Tunisian man who barreled his truck into a crowd in the French resort city of Nice was a "soldier" of the group.
A US official familiar with Washington's assessment said the attack was thought to have been carried out by a "lone wolf" inspired but not directed by Islamic State.
Ahead of the claim by the Islamic State group, French officials had not disclosed any direct evidence linking Bouhlel with jihadism.
A large truck mowed through revelers gathered for Bastille Day fireworks in Nice, killing more than 80 people and sending people fleeing into the sea as it bore down for more than a mile along the Riviera city's famed waterfront promenade. The gun-toting driver ploughed the 19-tonne truck at high speed two kilometres through a crowd that had been enjoying a fireworks display on France's July 14 national holiday.
The driver, identified by police sources as Tunisian-born Frenchman Mohamed Lahouaiej Bouhlel, 31, was shot dead by police.
Nice's palm-lined Promenade des Anglais was left strewn with bodies as hundreds fled in terror.
Dramatic video footage showed police surrounding the heavily damaged truck and firing through the windscreen to kill the attacker.
Meanwhile, the ISIS-linked Amaq network said his attack was carried out by "a soldier of the Islamic State", citing an unnamed security source.
The attack is the third of its kind in France since the beginning of 2015, and a state of emergency in place since 130 people were killed in and around Paris last November is to be extended for another three months.
Mohamed Lahouaiej-Bouhlel may not have acted alone.
His wife was reportedly taken into custody Friday morning, one of five people that the French prosecutor's office said had brought in for questioning, according to ABC. France is heading into elections next year, and the deeply unpopular President Francois Hollande is facing multiple challengers, from within his own Socialist Party, from the right-wing Republicans and from the far-right National Front.
After crisis talks in Paris, French Defence Minister Jean-Yves Le Drian recalled that IS had recently repeated calls to supporters to "directly attack the French, Americans, wherever they are and by whatever means".
Davis issued a statement on the family's behalf saying, "We are heartbroken and in shock over the loss of Brodie Copeland, an fantastic son and brother who lit up our lives, and Sean Copeland, a wonderful husband and father".