James Woods -- Sorry Ricky Williams ... Weed Gym Sounds Super Dangerous (VIDEO)

There will be no puff and pump for James Woods ... 'cause the Hollywood legend says Ricky Williams' new weed gym is a terrible and dangerous idea.

For those not up-to-date on the ganja gossip ... the ex-NFL star is a co-owner in a marijuana-friendly gym in San Francisco ... where members are encouraged to consume specialized doses of weed designed to boost their workout sessions.

So, when we saw James Woods out in Bev Hills and asked him if he'd ever be down for a dope workout -- the answer was a resounding HELLLLLL NO!

"I can't remotely imagine someone doing drugs and then working out," Woods said.