McGregor and his entourage entered the Barclays Center in Brooklyn and tossed a hand truck at a bus, causing a minor injury to a passenger, Sophia Mason, a spokeswoman for the New York Police Department, told the New York Times in an email.
McGregor surrendered to police at the department's 78th Precinct, but had not been charged as of late Thursday (local time) as police continued their investigation, a spokesman told Reuters.
Video footage circulated on social media showed McGregor running in a loading area and picking up an item and throwing it at a window on the back of the bus.
Clips of video shot from inside the van showed an object hitting and cracking the vehicle's windshield before the driver reversed away.
"This is the most disgusting thing that has ever happened in the history of the company," UFC president Dana White told website MMA Junkie (www.mmajunkie.com).
Russian lightweight contender Khabib Nurmagomedov is due to face Max Holloway in a showdown for McGregor's belt, which he won in 2016 but never defended, and White has said the winner of Saturday's bout during UFC 223 at the Barclays Center will be crowned undisputed champion.
Earlier in the week, Nurmagomedov confronted Artem Lobov, the 29-year-old McGregor's Russian friend, team mate and sparring partner, in a hotel in New York, an incident which may have provoked the Irish fighter.
White subsequently told reporters at the venue that Lobov would not be allowed to fight Alex Caceres as scheduled on Saturday.
