The latest such skirmish came around 10:30 PDT as some protesters began throwing bottles among a crowd that had reconvened in front of City Hall, where a haze of chemical smoke still hung in the air following a similar clash at the site about an hour earlier.
It was the fourth time police used tear gas in three hours.
Authorities have denied reports that they used flash bang canisters to help break up the crowds, saying the loud noises came from large firecrackers thrown at police by protesters. Police also report being attacked with rocks.
City Hall has been the site of conflict throughout the day. Authorities used a pre-dawn raid to dismantle an Occupy Wall Street encampment that had taken over a plaza outside the government headquarters for more than two weeks.
Police removed about 170 demonstrators who had been staying in the area overnight after repeatedly being warned that such a camp was illegal and they faced arrest by remaining. City officials said 97 people were arrested in the morning raid.
Helicopters scanned the area late Tuesday and scores of officers wearing helmets and carrying clubs patrolled the streets as protesters gathered only a few feet away.
The first scuffle broke out after hundreds of people made their way back to City Hall in an attempt to re-establish a presence in the area of the dispersed camp.
The protesters gathered at a library and marched through downtown Oakland and ultimately were met by police officers in riot gear. Several small skirmishes broke out and officers cleared the area by firing tear gas.
The scene has repeated itself several times since. But each time officers move to disburse the crowd, protesters quickly gather again in assemblies that authorities have declared illegal.
Acting Police Chief Howard Jordan told reporters at a late night news conference that authorities had no other choice, saying the protesters were throwing rocks and bottles at officers.
"We had to deploy gas to stop the crowd," he said, according to a KCBS report.
City officials say that two officers were injured. At least five protesters were arrested and several others injured in the evening clashes.
The Oakland site was among numerous camps that have sprung up around the country, as protesters rally against what they see as corporate greed and a wide range of other economic issues. The protests have attracted a wide range of people, including college students looking for work and the homeless.
In Oakland, tensions between the city and protesters have been escalating since last week as officials complained about what they described as deteriorating safety, sanitation and health issues at the site of the dismantled camp.
Associated Press reporter Marcus Wohlsen contributed to this report.