Comedian Tehran Von Ghasri saw Dave Chappelle's attacker sneak into his area at the Hollywood Bowl just before he tackled Dave ... shedding more light on how the whole thing went down.
We spoke with Tehran outside the Laugh Factory on Sunset Blvd. Thursday, and he says he alerted security the second the attacker snuck into his VIP section ... Tehran knew something was gonna go down but claims the Bowl's security crew couldn't care less.
Theran admits everything happened too fast to personally react once the attacker jumped on stage, but he thinks his words of warning could've prevented the entire thing from happening.
He's thankful Dave's security team got a quick handle on the guy ... he also attributes Dave's safety to two other things -- his workout routine and the attacker's clumsiness.