Jay-Z -- I Still Got Beef with Robert De Niro ... HE'S A FRAUD!

Seems Jay-Z is still holding his grudge against Robert De Niro ... and earlier today, he put the actor on BLAST during a live radio interview.

Jay was telling all to Power 105.1 in NY ... when the DJs asked Hova about his beef with Robert De Niro ... which came to a head last year when RDN reportedly dressed Jay down at a party because the rapper didn't return his phone calls.

It's clear from the interview ... Jay doesn't care for Robert -- and though he never took a direct shot, he spoke in very pointed generics ... saying, "I treat people based on who they are ... who they REALLY are."

He continued, "It doesn't matter who you are, everyone has to be respectful."