Will Smith‘s slap has at least one comedy club on its toes and ready to defend its talent at all costs — going so far as to post a very clear sign … no slapping allowed, period!

Dani Zoldan — who owns Stand Up NY in the Big Apple — tells TMZ … management decided to tape up a message in their storefront window that directly addresses the Chris Rock moment, as a way to discourage would-be copycats who might now feel emboldened.

The poster is in a bit of a meme format, with the snapshot of Chris getting slapped crossed out with a big “NO” sign streaked across the front, and a shot of Will crying right next to it.

Their message, “Comedians play a critical role in our society, especially during times of chaos and uncertainty. They make us laugh, bring perspective and remind us there are different ways of seeing our reality.” More importantly, they add … “Comics must be protected.”

Then comes a warning from Stand Up NY … “Heckling and physical abuse of comics is prohibited, and patrons will be immediately removed from the showroom.” Their crying WS photo has a description — saying that’ll be you if you get a little slaphappy on the premises.

Zoldan emphatically disavows Will’s actions, reaffirming his establishment’s note — that comedians are here to entertain us and make us laugh … and that they deserve respect.

As for other big-time comedy clubs … they seem to be keeping an eye on things — but not necessarily enacting any policy changes in response to the Will-Chris smack. That includes the Comedy Cellar in NYC, Carolines on Broadway and even the Laugh Factory here in L.A.