Deputies were called on Sunday (local time) to an outdoor shopping area in Calabasas, about 37km northwest of Hollywood, by a man who reported having just had an altercation with Bieber, the sheriff's department said in a press statement.
According to the statement, the man said he was taking pictures of Bieber, who was with his girlfriend, actress Selena Gomez, when the singer "physically battered" him.
Bieber's publicist with Island/Def Jam Music Group could not immediately be reached for comment.
A spokeswoman for the sheriff's department, Lillian Peck, declined to give further details about the nature of the alleged confrontation or any injuries suffered by the man.
But Peck said the man, who was not identified by police, complained of pain, and after requesting medical attention was treated on the scene by paramedics, then taken to a local hospital, where he was examined and later released.
Bieber, 18, who has professed a determination to maintain a squeaky-clean image, had left the shopping centre with Gomez, 19, before officers arrived, according to the man with the camera.
Peck said sheriff's deputies are investigating the case as a misdemeanour battery complaint and were looking for any possible eyewitnesses, but she did not know whether they had contacted Bieber about the incident.
The Hollywood news website TMZ.com reported that the man behind the complaint was a professional celebrity photographer.
Citing accounts of witnesses at the scene, TMZ said the paparazzo was blocking Bieber's car as the entertainer was trying to leave and that a scuffle ensued after Bieber got out of his car, asked the man to leave and the man refused.
TMZ also reported that after the altercation, a lawyer approached the photographer and suggested he could collect a lot of money by calling for an ambulance and filing a police report.
The cherubic-faced singer, discovered in 2008 through homemade music videos he posted on YouTube, released his first album at age 15 and rocketed to international fame on his way to logging 41 million fans on Facebook and 20 million on Twitter.
Bieber's latest hit single, "Boyfriend," debuted at No. 2 last month on the Billboard Hot 100 chart.
The Los Angeles Times reported on Sunday that the recent high school graduate paid $6.5 million for his first house, a 10,000-square-foot (929-square-metre) luxury home set in a gated community of Calabasas. Amenities are reported to include a movie theatre with stadium-style seating, a library, wet bar, wine cellar, guest house and swimming pool.
