Diallo, 26, was driving Hamraoui and another unnamed team-mate home after a team meal in Paris on 4 November when they were ambushed by two masked men.
Fellow France international Hamraoui was dragged from the car and had her legs beaten.
Diallo was arrested on Wednesday.
She had played in PSG’s 4-0 win over Real Madrid in the Women’s Champions League on Tuesday.
Hamraoui, 31, was treated in hospital and had stitches on her arms and legs.
In a statement, PSG said they were working with police “to shed light on the facts”.
As well as strongly condemning “the violence committed”, the club also added they had “taken all the necessary measures to guarantee the health, well-being and safety of players” since the attack took place.
Diallo, who has been capped seven times for France, joined PSG in 2016 and has made more than 60 appearances for the club but spent time on loan at Atletico Madrid last season.