Baltimore Kid Booted from Restaurant Holds Children's March Against Discrimination

Dallas Grant, the Black child who had to face an allegedly blatant act of discrimination ... is now taking it to the streets with other kids who are fed up with racism.

The 9-year-old activist held a children's march Monday in Baltimore, outside the Ouzo Bay restaurant he was blocked from eating at a few months ago. You'll recall, an Ouzo staffer sent Dallas and his mom packing because he was wearing basketball shorts, sneakers and a T-shirt -- very much like a white kid who had been allowed entry.

His mother, Marcia, tells TMZ about 70 people showed up in solidarity to march with Dallas, and a lot of them had custom shirts specially made for the cause. As you can see, even though it was a relatively small crowd ... they were still fired up and loud as heck.

Marcia says the point of the protest was to show kids and youth that their voices matter -- and that they too can fight against systemic racism, despite their young age. She tells us she still wants the restaurant group that operates Ouzo to admit what they did to her boy.

As for Dallas, we're told he feels he's making a difference ... and is happy with the turnout, despite the fact some of the patrons they encountered didn't seem too pleased with their demonstration. In fact, one woman even gave them the finger and complained to a waiter.

As we reported ... this isn't the end of Marcia and Dallas' crusade against this company -- they've already filed a lawsuit and are seeking damages, claiming the kid was traumatized.

As for Atlas Group -- which runs Ouzo and other chain restaurants in town -- they denied they were discriminating or being racist but did apologize for the initial encounter ... saying they fired some staffers over bad judgment.