The statue was ripped from its base on the 168th anniversary of one of Douglass' most famous speeches condemning slavery.
A spokesman for the mayor said it was part of a "reexamination" of monuments and statues that may "represent different things to different people."
Confederate statues toppled by protesters are "great artwork," said Trump, "as good as you see in France."
A statue depicting former President Theodore Roosevelt on horseback alongside Indigenous people on foot has been evicted from outside the American Museum of Natural History.
"Their statues pay homage to hate, not heritage. They must be removed," the House speaker said.
Worldwide protests over anti-Black racism and police brutality renewed efforts to take down Confederate monuments.
The memorial was unveiled on Sunday, the 64th anniversary of Parks' refusal to give up her bus seat for a white man.
Vandals set fire to a statue mocking Trump in Slovenia.
"More like Babe Lincoln, amirite?"
Jeff Goldblum had a perfect Jeff Goldblum response to the giant Jeff Goldblum statue that appeared in London.