Kanye West shouldn't just laugh off gang threats in L.A. ... so says Matt Barnes who says the real gangsters in Los Angeles don't mess around.
The ex-NBA star was leaving Catch when we talked about Kanye's appearance on "TMZ Live" -- including Yeezy's reaction to Daz Dillinger's recent call for the Crips to "f*** up Kanye."
"You gotta be careful," Barnes said ... "They don't play out here with gangs so you're treading on thin ice.