A man threatened to assault a member of staff at a service station on the A47 near Peterborough after being unable to fill up his car.
The incident happened at about 4.30pm on December 22 at Snax 24 on the A47 at Wansford.
A silver Peugeot 307 driven by a woman pulled onto the forecourt and the man got out and attempted to put fuel in the car but the pump was not authorised.
The man, who had been aggressive to staff at the station before, then grabbed the member of staff and threatened to assault him.
The victim managed to pull away and sound an alarm.
Police have released a CCTV image of the man they want to trace.
Anyone with information should contact PC Adrian Anderson, from Cambridgeshire Constabulary, on 101.
They can also call Crimestoppers, anonymously, on 0800 555111 and quote crime number 0493381214.