The men were brought in for questioning on Monday and are being held by police, numerous French media outlets reported on Wednesday morning.
One of the men is understood to have been pictured with the killer beside the truck that was used in the attack, and both are said to be in his entourage.
Police arrested the suspects as investigators try to determine whether the killer, Tunisian Mohammed Lahouaiej-Bouhlel, got logistical support for the attack, a source close to the case said.
Five other people -four men and one woman - have been arrested so far in connection to the attack on the suspicion of influencing or supporting Bouhlel.
Prosecutor Francois Molins said that correspondence between the suspects and Bouhlel -- shot dead by police during the attack -- indicated they had been in on the plot.
The attack was claimed by the Islamic State group.
However while Bouhlel had gruesome images on his computer related to the group, as well as its rivals Al-Qaeda, investigators have not turned up evidence of his sworn allegiance to the group.