"I was in the wrong," McGregor said. "That man deserved to enjoy his time in the pub without having it end the way it did.
"I must come here before you and take accountability and take responsibility. I owe it to the people that have been supporting me. I owe it to my mother, my father, my family. I owe it to the people who trained me in martial arts. That's not who I am."
The incident is now being investigated by police and McGregor said he is ready to accept any punishment meted out.
"Whatever comes my way, I will face it," McGregor said. "Whatever comes my way, I deserve it. I will face this head on. I will not hide from it. I was in the wrong. It was completely unacceptable behavior for a man in my position."
The 31-year-old, an icon of the UFC, meanwhile said he is keen to return to fighting despite announcing his retirement in March.
"I must get my head screwed on and just get back in the game and fight for redemption, retribution, respect -- the things that made me the man I am," McGregor said. "And that's what I will do."
McGregor has not fought since being battered into submission by arch-rival Khabib Nurmagomedov in October last year.
However he insists he is ready to make a comeback despite his lengthy layoff.
"Mine is gonna be the greatest (comeback) of all," McGregor said. —AFP