The UFC star was at the pub, which was not damaged, on the day it was attacked, according to social media posts.
The Black Forge Inn in Drimnagh Road, Dublin was attacked on Wednesday night.
No damage was done.
The former UFC champion, 33, was in the pub earlier on Wednesday, according to social media posts.
Gardai are appealing for witnesses to come forward.
“Gardai are particularly keen for anyone with camera footage from the area overnight to make this available to them,” the force said in a statement.
Anyone with any information is asked to contact Crumlin Garda station on 01 666 2000.