By TMZ

Las Vegas strip clubs are getting a stern warning from cops -- DON'T LET FLOYD MAYWEATHER INSIDE ... because he sexually harasses strippers ... something Floyd denies.

TMZ Sports has learned ... the Vice unit of the Las Vegas Metro Police Department contacted multiple strip clubs in Sin City ... telling them Floyd and his crew have run roughshod in various clubs, manhandling the girls.

As one law enforcement source put it, "He [Floyd] goes in and pulls a 'Do you know who I am' and does inappropriate things with some of the women."

We spoke with honchos from multiple strip clubs who tell us they will NOT heed the warnings, because they've never had a problem with Floyd. Plus, everyone knows he spends a TON of cash.

Sources close to Floyd tell us the boxer is adamant he has NEVER done anything wrong at a strip club -- particularly with women -- and has no idea why cops would have him in their crosshairs.