Offset and his entourage’s plans to enjoy the legal California cannabis went up in smoke last night … a security guard is accusing the former Migos rapper of assaulting him — and sending him to the hospital!!!

Multiple sources tell TMZ Hip Hop that Offset and several other guys popped up at a popular dispensary, MedMen LAX, around 9:30 PM … and a dispute arose over whether Offset presented ID, prohibiting him by law from buying or even touching any marijuana products.

Reps for Offset call the claims ridiculous … he had just gotten off a flight at the nearby airport, and identification is an obvious requirement to hop on a commercial plane, and they say ID was in his possession at the shop.

Offset says he was in the process of presenting the ID when the security guard was aggressively rushing him … hawking spit in his face, causing a fight to break out.

When more of MedMen’s security got involved in the altercation, our sources say Offset punched the guard … and the guard doused Offset and his entourage with mace!!!

Police were then called to the scene, and we’re told Offset and his team fled the scene.

Paramedics were also dialed up, and the guard was transported to a local hospital after the attack. It’s unclear what the extent of his injuries were.

We’re hearing the security guard is believed to have pressed charges against Offset — who’s maintaining his innocence.