Israel Adesanya says he was not the aggressor during a recent confrontation with a man in New Zealand ... claiming the other guy started the whole incident by hurling a racial slur.
A source close to the UFC superstar tells TMZ Sports ... as Izzy was parking his car on a roadway in his home country, the guy came out of nowhere and started calling him the N-word.
Soon after, our source says the man challenged Adesanya to a fight.
In video filmed by a witness -- which has now gone viral on social media -- it's hard to make out what either dude is saying .