Several hundred demonstrators gathered in Lower Manhattan on Thursday to protest the Trump administration’s crackdown on diversity, equity and inclusion policies and its effort to exert control over policing in Democratic-led cities.

The protest, called the “March on Wall Street,” was led by the Rev. Al Sharpton, whose National Action Network had organized it. He marched alongside Martin Luther King III and Assemblyman Zohran Mamdani, the Democratic candidate for mayor of New York City.

In a statement before the march, Mr. Sharpton said that the Trump administration’s attacks on D.E.I. this year had served as a “prelude” to its recent threats “to take over American cities led by Black mayors.”

In recent months, the administration has sent National Guard troops and active-duty Marines into Los Angeles, and has sought to control the police force in Washington, D.C. Both cities have Democratic mayors who are also Black women — Karen Bass in Los Angeles and Muriel Bowser in Washington.

Mr. Sharpton laced into Mr. Trump in his statement on Thursday. “If we leave him unchecked on D.E.I., if we do not get out and march, if we do not speak up, he will completely erase the freedoms our parents and our grandparents fought, bled and died for,” Mr. Sharpton said, adding that the march on Thursday was meant to remind the president of “the power of Black Americans and their dollars.”

Organizers said that protesters had come from Kentucky, Tennessee, Florida, California, Michigan, Pennsylvania, Ohio, Maryland and Washington, D.C.