Conor McGregor is reportedly under investigation in Ireland -- again -- after allegedly punching a man Saturday in a pub in Dublin.
The UFC superstar was at the Marble Arch pub in Drimnagh (a suburb of Dublin) when he was approached by another patron who thought Conor was acting like a jerk, according to the Irish Mirror.
The patron reportedly talked trash to Conor about his loss to Khabib Nurmagomedov saying, "The Russian battered you" ... and that's when Conor snapped and punched.
We called Ireland's Garda Síochána -- the country's police force -- who wouldn't identify Conor by name but did confirm an investigation of an alleged April 6 incident at the Marble Arch.
"No arrests, matter under investigation."
We also called the pub -- but an employee hung up on us as soon as we asked about Conor.
Calls to McGregor's rep have not been returned.
It's just the latest in a long list of legal problems for Conor ... who's also facing criminal charges for an alleged incident at a Miami hotel last month.
He's also reportedly being investigated in a rape probe in Dublin stemming from an alleged incident at a hotel in Ireland back in December. Conor's rep has called the report a "rumor."
Of course, Conor was convicted in a bus attack incident back in 2018 -- when he threw a steel dolly at a UFC bus ... injuring multiple people inside the vehicle.