According to City News Service, the officers blended in to learn about protestors' intentions and to see whether they planned to resist or use weapons against police.
Nearly 300 people were arrested during Wednesday's predawn raid at City Hall Park.
Police are downplaying the significance of the undercover work, saying Occupy meetings were public and information was easy to get.
Meanwhile, Occupy L.A. protesters once again took to the streets on Saturday, with one person reportedly being arrested by police.
The person was reportedly arrested at the Bank of America branch at 6th and Hill streets in downtown Los Angeles.
Demonstrators had gathered there, with some allegedly banging on the locked doors.
As many as 200 people walked from Pershing Square to City Hall. For the most part, the demonstration was peaceful.
See photos of protesters gathered around City Hall past the eviction deadline.
