Olympian Tommie Smith -- I'm Boycotting James Woods ... Calling Kaep A 'Dirtbag' Is Wrong

... one half of the iconic Black Power demonstration from the '68 Olympics ... says he's done watching James Woods movies ... 'cause Woods called Colin Kaepernick a "dirtbag."

Woods has been all over Kaep -- and the NFL -- telling our cameras he's boycotting the league for it's refusal to discipline the 49ers QB over his national anthem protest.

But it's Woods' name-calling of Kaepernick on Twitter -- where he called Kaep a "piece Of S@#t" and a "dirtbag" -- that has Smith steaming mad.

Of course, Smith and fellow sprinter John Carlos are the OG's of the sports protest game .