Ventura police said the incident happened just before 6 p.m. Saturday in the 3400 block of Loma Vista Road.
According to police, a 23-year-old woman was getting out of her car when the suspect approached her from behind and demanded unspecified property.
The woman turned over her belongings, then the suspect punched her in the face and fled the scene. He was last seen running in the area of St. Pauls Drive and Loma Vista Road.
The suspect was described as a Hispanic man between the ages of 20 and 25. He was about 6 feet tall and 180 pounds.
The woman sustained minor injuries to her face.
Anyone with information is asked to call Crime Stoppers at (800) 222-TIPS.