Both- male rabbits behavior changes dramatically when it matures and you do not get it neutered. Do yourself a favor and get your boy in immediately for a neuter. You're dealing with hormonal aggression and territory issues.
Not only that but you're increasing his potential lifespan. He's a large animal- you'd neuter a cat, why not a rabbit?
Check this out-
Add- It has nothing to do with wild prey v. predator instincts. The dynamic of house pets is nothing like wild animals. A cat may hunt rabbits outside but give no notice to a rabbit in the home. We're talking about a different set of rules.
Add- Already neutered eh? Then no- it's not puberty. I'd say then that it's actually a dominance issue. Probably he's dominant over your female (probably even you too), but not the cat. And he's trying to establish his dominance over your cat. Teach him who's boss! Gently-
When he's acting like a brat, gently but firmly (it's possible- haha) hold his head down to the floor. This mimics a natural rabbit behavior, one they use to dominate one another and develop their heirarchy. He will probably squirm and fight back but be persistant and he'll learn he's not the little dictator he thought he was.
Then again, some rabbits just hate cats.