The 29-year-old Irish fighter was charged with assault and criminal mischief after an incident at the Barclays Centre in New York, and has now entered into plea negotiations.
He and his co-defendant Cian Cowley were released on bail after a brief court appearance in Brooklyn and are due to return to court on 26 July.
In a statement outside the court, McGregor said: “I regret my actions that led me here today.
“I understand the seriousness of this matter and I am hopeful this will get worked out.”
Assistant district attorney Janet Gleeson said the case had not been presented to a grand jury for indictment because of the ongoing plea negotiations.
Video footage of the brawl appears to show McGregor and his entourage using a metal barricade and other objects to smash windows on a bus filled with fighters.
The melee happened after a media event to promote a series of UFC fights at Brooklyn Arena.
One fighter on the bus was hit and cut by an object thrown through a window, while another had the cornea of his eye cut by the glass as it broke into dust.
McGregor handed himself in to police soon after the scuffle and was released on $50,000 bail.
McGregor cheered Cowley during a fight in Belfast over the weekend, and the pair flew into the US on a private jet for the hearing.