The incident took place on Monday, April 4 at 11.15am.
PC Craig Virco said: “The man, who had a light brown dog with him became abusive towards ticket office staff after his card was declined whilst attempting to purchase a ticket.
“He then singled out a male member of staff and threatened him with violence, leaving him extremely shaken and fearing for his safety. The man then left the station.”
Officers want to speak to the man in the image in connection with this incident.
PC Virco added: “I believe this man will have vital information which could greatly assist our investigation.
“If you know him please get in touch. This type of abusive and threatening behaviour towards members of staff who are simply doing their job is not acceptable.”
Anybody with information about the incident, should call on 0800 40 50 40 or text 61016 quoting reference 236 of 5/5.
Alternatively, information can be passed to the independent charity Crimestoppers on 0800 555 111.