A teenage girl was pushed into a road while out running in Bury St Edmunds on Tuesday night.
She was running down Tollgate Lane at around 8.15pm when she was approached by a man from behind.
He pushed her over and into a road, forcing a car to swerve.
The girl received minor injuries and damaged her phone.
Police are urging anyone who witnessed the incident to contact Pc Shelley Nailard on 101 - quoting reference number BU/15/219 - or Crimestoppers, anonymously, on 0800 555111.
They are particularly keen to talk to the driver of a small dark car who swerved to avoid hitting the girl.