Officer Karen Rayner said one or two police cruisers were damaged and reinforcement officers were called in from throughout the city to help disperse the crowd.
Police department strike teams had pushed people from the immediate area around the Staples Center into surrounding neighborhoods and were attempting to break the crowds into progressively smaller clusters, Grady said.
The department had declared a citywide tactical alert, meaning that all officers on duty were to remain on duty until the crowds had been completely dispersed, she said.
The Lakers beat the Orlando Magic 99-86 in Game 5 of the NBA finals Sunday night to win their 15th championship.
Television reports also showed small crowds of people parading through the streets of East Los Angeles, where excitement over the Lakers' Game 4 win Thursday night spilled into the streets, with rowdy fans swarming vehicles trying to pass through the area.
In 2000, after the Lakers won their first NBA title in 12 years, fans rioted outside Staples Center, burning police cars and leaving more than 70 vehicles damaged, many at nearby auto dealerships. At least 11 people were arrested and a dozen were injured.
Sunday night's crowd appeared to be the remaining members of a throng of hundreds of ecstatic fans who streamed onto the sidewalks from the bars and restaurants surrounding the Staples Center, where the Lakers play home games.
Before the game, Mayor Antonio Villaraigosa said if the Lakers win they should have a victory parade in Los Angeles, despite the city's budget woes.
Villaraigosa said he would work with the private sector to help fund the celebration, which was expected to occur on Wednesday.
