DIDDY & MTV THROW A SWEET SIXTEEN PARTY FOR JUSTIN & NICKI MINAJ WAS HIS DATE!

Diddy was on a mission to throw his son Justin Dior the ultimate Sweet Sixteen on Saturday night, and no one was going to stop him.

Spies at the M2 Ultralounge bash say the music mogul almost got into an altercation with a publicist early in the evening, when the flack tried to get in some personal business time with him.

"Diddy was yelling about how it was his son's birthday and not a night to talk about work," a partygoer dishes. "He really ripped into him, but the guy totally deserved it. He was out of line."

But the minidrama couldn't take away from the extravagant fete or Justin's spotlight: Diddy had his eldest son sit above the packed crowd on a throne that was on the stage, all while MTV cameras rolled for an upcoming episode of "My Super Sweet Sixteen."

And the line-up of performers wasn't too shabby, either. The crowd went wild when the likes of Fabolous, Lil' Kim and Jim Jones took to the stage to perform.

Diddy also didn't skimp on the gifts. He presented Justin with a brand-new silver Maybach (which sat outside the W. 28th St. hot spot wrapped in a red bow) and a uniformed driver to escort him around New York City — because, at 16, Justin is just now learning how to drive.

In a smaller — but just as exorbitant — package: The doting dad gave his son a check for a cool $10,000, which we hear the miniphilanthropist has decided to donate to Yele Haiti.

And while the kids were having good, clean fun downstairs, the celebrities that attended the fete retreated to a private upstairs section for a more adultlike experience.

The aforementioned singers as well as crooners Trey Songz and Juelz Santana joined the cast of (what else?) "Jersey Shore" behind a velvet curtain, where they were all certainly having a good time.

"When Snooki [Nicole Polizzi] left around 10 p.m., she snuck out a back door and absolutely wreaked like booze," one partygoer said. "The over-21 party was even more wild than the one downstairs."