A spokesperson for the Irish police said they are investigating the incident at the pub: "No arrests have been made. Investigations are ongoing."
This comes after a series of controversies for the former UFC two-weight champion.
McGregor faces court in Miami this week after being arrested and charged with multiple offenses last month – although he will not have to appear in person. He was accused of stomping on a fan's phone.
He is also under investigation in Ireland after a woman accused him of sexual assault, according to reports.
The New York Times reported that the alleged assault occurred in December. The Irishman has not been charged but is under investigation.
It is also a year since McGregor attacked a bus carrying UFC fighters, including his rival Nurmagomedov, at a media event in New York.
McGregor pleaded guilty to disorderly conduct and was sentenced to three days of anger management courses, five days of community service, while also copping a six-month suspension and $50,000 fine from the UFC.
Last week, the troubled star was slammed on social media after tweeting a "racist" insult at Nurmagomedov's wife.
In a now deleted tweet, McGregor posted a picture of the Russian champ's wife wearing a religious veil with the caption: "Your wife is a towel mate."