The Tuesday confrontations came as officials complained about what they described as deteriorating safety, sanitation and health issues at the camp.
The same concerns have been raised about camps in San Francisco and Los Angeles.
Protesters at San Francisco's Justin Herman Plaza were bracing for a police raid early Thursday when they were visited by several city supervisors and a state senator. The officials expressed their support.
San Francisco police warned the protesters earlier in the week that they could be arrested on a variety of sanitation or illegal camping violations.
There were reports that police in riot gear had set up a staging area near the plaza early Thursday morning. But police spokesman Carlos Manfredi said officers routinely gather to practice crowd control procedures, and there were no plans to shut down the Occupy protest.
He said police were still seeking voluntary compliance.
"We're still continuing to monitor the situation," he said.
Anti-Wall Street protesters camped out in downtown Los Angeles say they're planning to continue their demonstration indefinitely, although both they and the mayor's office were eyeing alternate sites.
Occupy LA organizer Gia Trimble said the protest has swelled to nearly 500 tents on the lawn around City Hall and organizers are eyeing possibly moving the encampment to a larger piece of city property nearby in downtown Los Angeles.
Associated Press writers Jason Dearen and Sudhin Thanawala in San Francisco, and Christina Hoag in Los Angeles contributed to this report.
- Live at the GOP convention: Donald Trump...
- Trump speechwriter apologizes for Melania...
- Thunderous boos for Cruz for refusing to...
- 17 arrested in flag-burning melee outside GOP...
- Trump's moment: Speech to close GOP...
- Cruz: Not supporting candidate who wages...
- Rupert Murdoch vows Fox News without Ailes is...
- NBA moving All-Star Game out of Charlotte,...
- Utah delegates finally stand and cheer... 93
- Utah GOP delegates finally fired up... 75
- Obama rejects Trump depiction of US in... 40
- The day after: Lee defends Cruz at GOP... 32
- Trump speechwriter apologizes for... 27
- Police give all-clear in Munich... 27
- Thunderous boos for Cruz for refusing... 22
- Ohio Mormon offered invocation at... 22