Vegas 'Cannabis Cup' Frowning On Weed After White House Threat

President Trump's promise to get tough on marijuana is harshing the mellow at a famous cannabis festival in Las Vegas, which is suddenly abiding by federal laws -- meaning NO GETTING HIGH.

Organizers for this year's HIGH TIMES Cannabis Cup -- which kicks off in March -- tell us weed is NOT allowed at the event this year, and that goes for headliners Ludacris, Chief Keef and Cypress Hill's B-Real too.

Even though recreational weed is legal in Nevada, we're told the feds informed the Moapa Paiute Tribe -- who own the land where the event is going down -- that federal law prohibits transport, possession, use or distribution of marijuana.

The threat seems clear: We'll be watching. Plus, White House press secretary Sean Spicer recently said point-blank they'd be cracking down on weed.

HIGH TIMES reps say they're still expecting a great event, but want to comply to help the cannabis industry "continue to gain legitimacy and social acceptance."

Talk about a buzzkill.