Los Angeles Police Department spokeswoman Rosario Herrera confirms a complaint was made on Monday, and officers are interviewing the alleged victim.
Herrera says, "Detectives are currently interviewing the victim. It was reported at 10.30 p.m. Monday night to our Devonshire location and occurred earlier in the day in the Valley."
"As of right now, no arrest has been made and detectives are currently interviewing the victim."
Reports suggest the investigation is in connection with an incident at Sherman Oaks Castle Park in California, where Bieber and his entourage were playing miniature golf on Monday.
According to TMZ.com, the singer allegedly snatched a woman's phone after accusing her of trying to take pictures of him.
Bieber is already facing a slew of legal issues - he will go on trial in July in Miami, Fla., for driving under the influence, resisting arrest and using an expired licence. He is also facing prosecution in connection with the alleged assault of a limousine driver in Toronto, Canada, last year