McGregor and friend Cian Cowley, both charged in the April 5 attack, made a roughly 90-second court appearance Thursday morning, in which a prosecuting attorney mentioned that the pair and their attorneys are in plea negotiations with prosecutors.
Both are due back in court July 26. They have been free on bail since shortly after the incident, and have been allowed to travel to their native Ireland.
They returned to New York this week for the court date.
Prosecutors also have said McGregor punched a security guard at Barclays Center during the melee. He was charged with felony criminal mischief, as well as charges of assault, attempted assault, menacing and reckless endangerment.
Cowley, who is accused of throwing a chair at the bus, was charged with criminal mischief, assault and reckless endangerment.
The bus was carrying fighters who were scheduled to compete in April 7's UFC 223 bouts at the Barclays Center -- including Khabib Nurmagomedov, who was to fight for McGregor's former lightweight title. The fighters had just wrapped up a media-day event at the arena.
White said McGregor had "some sort of beef" with Nurmagomedov.
Nurmagomedov wasn't injured in the attack, and went on to defeat Al Iaquinta for UFC's lightweight title two days later.
But the UFC said two fighters suffered injuries and had to abandon their April 7 bouts: lightweight fighter Michael Chiesa, with head and facial cuts from broken glass, and flyweight Ray Borg, who suffered corneal abrasions.
CNN's Tony Marco contributed to this report.