The Toulon criminal court took the decision after a French prosecutor called earlier this month for Armitage to be handed a suspended jail term of between five and six months, and a fine of 5,000 euros.
"The court considered that there were too many grey areas in this case at the end of a particularly rushed police investigation," Armitage's lawyer Virginie Pin told Reuters.
Flanker Armitage is accused of assaulting a 30-year-old tennis instructor in a restaurant in Toulon in mid-December where he was celebrating with team mates after defeating English rugby team Leicester in the European Champions Cup.
Armitage has denied any wrongdoing, saying he was "very inebriated" and adding that he did not remember having hit anyone voluntarily.
Armitage, one of the key men in Toulon's rise to the top of the French and European game, has been frozen out of the England squad because the Rugby Football Union does not select overseas-based players. He has won five international caps.