Officers helped city workers temporarily close Lownsdale Square Park and Chapman Square Park at about 5 a.m., the Portland Police Bureau said in a statement. People were given 10 minutes to leave and were arrested if they refused to do so.
"The parks will remain closed until needed repairs are made and the parks are ready to reopen for all to enjoy. The Police Bureau will assist other City bureaus to facilitate park closure and repair to lawns, bathrooms, benches, and public art," the bureau said in a statement.
The Multnomah County Sheriff's Office, which helped in the operation, added: "These parks have been the center of nightly demonstrations and will reopen when the needed repairs are made."
Details on the arrests weren't immediately released.
Occupiers infamously set up a similar camp in Seattle last month after police officers abandoned a police precinct. The occupation was tolerated by city officials for weeks before being broken up after several shootings.
Members of Antifa, a far-left anarcho-communist group, were involved in the Seattle and Portland occupations.
Violent demonstrators have gathered nightly to assault buildings and law enforcement officers in Portland since late May, inflicting tens of millions of dollars in damage.
Late July 14, groups used makeshift barricades to stake out portions of the parks, dubbing the space the Chinook Land Autonomous Territory, or CLAT.
Feds, City ClashPortland Mayor Ted Wheeler, a Democrat, has repeatedly condemned law enforcement's response to the demonstrations, particularly from federal officers.
Mobs have targeted the Mark O. Hatfield Courthouse, a federal building, attempting to set fire to the structure and assaulting some of the officers who have emerged to try to protect it. Critics say the use of force by law enforcement, including CS gas, isn't necessary.
Wheeler said this week that he spoke with acting Homeland Security Secretary Chad Wolf. Wheeler said his biggest concern "is the violence federal officers brought to our streets in recent days, and the life-threatening tactics his agents use."
"We do not need or want their help," he added in a series of social media posts. "The best thing they can do is stay inside their building, or leave Portland altogether."
The mayor said his plan is to "protect our community. Clean up our city. And re-open."
Mark Morgan, the acting commissioner of U.S. Customs and Border Protection—a Homeland Security agency—said on July 16 that the people involved in the mayhem in Portland are criminals.
"These are not protesters. When you talk about what's going on in Portland, for example, these are criminals. These are individuals that are planning, organizing—with premeditation—to destroy federal property and harm federal officers and agents," he said during an appearance on "Fox & Friends."
Morgan suggested that President Donald Trump will take executive action soon on the matter.
"I don't want to get ahead of the president's announcement, but look, the Department of Justice is going to be involved in this, DHS is involved in this, and we're really going to take a stand across the board," he said. "And we're going to do what needs to be done to protect men and women of this country."