Conor McGregor says he was ringside at the MMA fight in Dublin -- in which a fighter was beaten so badly, he died from his injuries ... and calls the whole situation "truly heartbreaking."
Conor was at the fight to watch his teammate Charlie Ward take on Portuguese fighter Joao Carvalho. Joao lost by TKO in the 3rd round ... and died a few days later from head injuries suffered in the fight.
"Terrible news regarding Joao Carvalho," McGregor said in a statement.
"To see a young man doing what he loves, competing for a chance at a better life, and then to have it taken away is truly heartbreaking.