It seems Oliver Stone is not a huge fan of his film “Natural Born Killers” … and he blames one of the film’s stars for “ruining” the iconic ’90s flick … none other than Robert Downey Jr.!

You know the movie … ‘NBK’ was condemned in the media when it dropped in 1994 for its brutal depiction of violence … and it even inspired some real-life copycat crimes. Still, the highly controversial film was praised by most critics.

But now, it seems Oliver is among those who also took some issue with the flick starring Woody Harrelson and Juliette Lewis. … and he holds the “Iron Man” actor responsible for his disdain.

In a recent oral history of the film by Esquire … OS blasts Robert for his “slapstick bulls***” acting while playing journalist Wayne Gale … even going so far as to say he told the actor at one point — “You’re ruining my movie!”

That’s a pretty brutal review … but in fairness … RDJ played the Australian as a bombastic kook and big-time fame whore in the unhinged — but quite memorable — role.

RDJ probably won’t be too broken up by Oliver’s remarks … after all, the dude just landed his first Oscar for “Oppenheimer” and became one of the biggest stars on the planet thanks to his Marvel reinvention.