Justice Smith's proud of his new movie that features a prominently Black cast ... but he's warning white people to avoid using the movie's full title -- or else they're getting side-eyed.

We got the actor out at LAX Wednesday and asked him about his new comedy titled "The American Society of Magical Negroes" ... and he (jokingly) recommended whites shorten the title to simply 'American Society' ... although, again, he's totally kidding around.

If you haven't heard about the movie yet, here it is in a nutshell .

.. a man named Aren (played by Smith) joins a secret society of Black people who use magic to keep white people happy -- and therefore docile. "The Color Purple" star David Alan Grier from 'The Color Purple' and Nicole Byer from "Good Burger 2" also star in it with him ... among others.

Funny enough -- JS' joke matches one his character says in the film's trailer ... when he tells his mentor they should consider changing the name of their org to "The American Society Of Magical Black People." Life imitating art, baby!

Anyway, Justice tells us there's a certain level of truth to the satire that's depicted in his flick .

.. and he says it pokes fun at the "magical negro" trope that's pervaded films depicting Black characters through the years. If you don't know what it is ... see the trailer above.

Smith says he'll be doing a ton of traveling for the new movie ... including going to the Sundance Film Festival where the movie's set to premiere. In fact, Justice's got two movies premiering there this year ... 'American Society' and "I Saw The TV Glow."

"The American Society Of Magical Negroes" gets its wide release on March 22 .

.. but maybe buy your tickets online instead of shouting the name at the ticket window.

Just saying ...