As many as 2,000 people marched for hours through the streets after starting in Pershing Square. They traveled through surface streets as a police presence remained close by.
A little after 8 p.m. they ended their march for a short time and arrived in front of City Hall. Many people held signs and gathered on the steps and sidewalk.
"We've all made a huge mistake, refuse to accept it," protester Hunter Pritchett said of the presidential election's outcome.
The demonstrators, some of whom carried a banner reading "#NOTMYPREZ," then made their way back to Pershing Square and continued on to L.A. Live before turning northward again.
A man in the crowd was seen spray-painting a Los Angeles Police Department vehicle. About 20 minutes later, he was taken into custody by officers in riot gear.
It was unclear if any other arrests were made in connection with Friday night's protest.
California Highway Patrol blocked off entrances to the freeways all around downtown to make sure the group did not attempt to stop traffic.
The string of nightly demonstrations come after Trump was elected president of the United States on Tuesday.
Hundreds of students at UCLA and UC Irvine took to the streets to protest the results right after the election.
Some violence was reported at the Oakland protest late Tuesday night, when some demonstrators set fires, broke windows and sprayed graffiti on downtown businesses.
About 11,000 people are expected to descend on L.A.'s MacArthur Park Saturday morning for another anti-Trump protest.