Terrell Owens just ripped Stephen A. Smith for his Colin Kaepernick criticism ... and straight-up told the ESPN star his white cohost, Max Kellerman, "almost seems blacker than you."

SAS has been one of Kap's biggest detractors since his NFL workout over the weekend ... essentially blasting the QB for not publicly explaining his situation further.

TO has taken major issue with the TV talent's takes, and even sent Stephen A. a private text message about it -- so Smith invited Owens on "First Take" to air it out.

The two were arguing alongside cohost Max Kellerman over the issue ... when Owens interrupted the discussion to say, "Max almost seems blacker than you, Stephen A."

SAS was FURIOUS about the comment -- calling a "timeout" and telling Owens he "crossed the line."

"Imma check you right now," Smith said. "You done crossed the line."

Eventually, Owens explained his comment by telling Smith, "You're taking it as disrespect. There's no disrespect ... it's tongue-in-cheek."

Doesn't seem Smith saw it that way ... 'cause he went on his ESPN Radio show later Thursday and said he wished he were on another network so he could curse about the whole incident.

Owens hasn't talked about the drama on social media yet ... but we're sure a tweet or IG post will be coming soon.