CNN Anchor Don Lemon -- Jonah Hill Treated Me Like 'The Help'

CNN anchor Don Lemon says Jonah Hill is a rude, arrogant a-hole who treated him like "the help" when he tried to shake the actor's hand during a recent run-in at a hotel ... and now he's trashing the actor to anyone who will listen.

For the past 24 hours, a very bitter Lemon has been on a mission to blast Hill across multiple media platforms ... starting on Twitter ... and ending on "Starting Point with Soledad O'Brien."

It all began yesterday ... when Lemon tweeted, "Said hi to @jonahhill in hotel. Think he thought i was bellman. Didn't know his name til bellman told me. A lesson to always be kind."

Hill -- clearly upset -- fired back, "I said hi what do you want me to do move in with you? I was in a hurry. Didn't realize you were a 12 year old girl. Peace."

Jonah added, "I walked out of the restroom and found you waiting for me. Shook hands, said hi and was on my way. Sorry if you found that rude."

The two continued to cyber-spar ... until Don went on CNN this morning to further exploit the feud and said, "Jonah Hill doesn't owe me anything, and he may have been having a bad day ... but Jonah Hill treated me like the help."

"Normally it doesn’t bother me, but I was done ... because I’d been taught by mother to always be kind to people," Lemon said.

Don also said he expected an apology from Jonah. Don't hold your breath.