U.S. Olympic legend John Carlos -- who famously raised the black power fist at the '68 Games -- is warning Shaquille O'Neal about criticizing Colin Kaepernick's protest ... saying he's going to wind up on the wrong side of history.
Earlier this month, Shaq was adamant he would never follow Kaep's lead, cited relatives in law enforcement and military, and said, "There are other ways to get your point across."
Well, that obviously struck a chord with 71-year-old Carlos, who was in D.C. to be honored by President Obama at the White House.
He told TMZ Sports, "To Shaq and all the other guys that want to be the naysayers to what Kaepernick is doing, all I can say to them is they better be careful on how they gonna come out ... on which side of history they're gonna come out in the future."
"I think they're gonna come out on the wrong side of the street."
As for Obama, he praised Carlos and Tommie Smith for their legendary protest -- saying, "It woke folks up and created greater opportunity for those that followed."