Barton, 24, appeared at Trafford Magistrates' Court to face one count of assault occasioning actual bodily harm.
Liverpool-born Barton was arrested after the incident at City's Carrington training ground on May 1.
The charge carries a maximum sentence of five years in jail if he is found guilty.
Barton was suspended by City after the incident, and sold to Newcastle in June in a £5.8 million deal.
He is now out of action for the north-east club after fracturing a metatarsal in his left foot during a pre-season friendly last month.
Barton was given unconditional bail and ordered to appear back at Trafford Magistrates' Court in Manchester on October 4 at 9.30am.
Prosecuting, David Alcock described the incident as a "vicious attack".
Barton, who was using crutches, spoke to confirm his name and address and to enter a plea. The brief hearing lasted 10 minutes.