'Barbershop' Actor: I Was Kicked Off Plane Because I'm Black

United Airlines is investigating a complaint made by an actor who appeared on the TV show "Barbershop" after he claimed he was kicked off of a flight simply because he was black.

Michael Colyar claims he was booted from his flight at Dulles International Airport in Virginia after he refused to allow a flight attendant to move his luggage from the overhead storage bin ... so a white passenger could stow her bag there instead.

Colyar claims the flight attendant gave him dirty looks when he denied her request -- so he inquired about filing a complaint. That's when Colyar says he was approached by security, who removed the actor from the flight.

Colyar blogged about the incident ... saying, "The flight attendant and her friend got just what they wanted, the n**ger off the plane. I'm sure they feel a great triumph in putting an uppity n**ger in his place."

He adds, "At the least I should be suing United Airlines for theft of services, public humiliation and defamation of character."

United Airlines tells TMZ ... "As a global airline with a diverse workforce, United has zero tolerance for any type of discrimination and we take every such matter seriously. We spoke to Mr. Colyar Wednesday so that we can address his concerns, and committed to get back to him as we learn more from our coworkers and other customers onboard.”