According to social media posts, the party happened Friday night at the Sassafras Saloon on Vine Street.
In a video posted by the website Knock-LA.com, several men are seen responding "Yeah" when asked if they are arriving at the bar for "the LASD party."
But in a statement, the Los Angeles County Sheriff's Department said: "The persons identified in the video are not employees of the Sheriff's Department and this event was not hosted by the LASD."
The Los Angeles Police Department said it was investigating whether any of that agency's officers were in attendance.
"We are trying to identify LAPD employees, who may have been in attendance," the LAPD said in a statement. "The Chief of Police has made his expectations clear and Department notices have been distributed, that every employee shall wear a face covering and practice social distancing when possible at work and in the field."