A public order offence took place in Deightonon Monday at around 10.25am.
Two males are believed to have been involved in a dispute at a bus stop on Riddings Road near to the junction of Browning Road, when the victim tried to intervene.
The victim, a 65 year old man, was then threatened by one of the people involved in the dispute.
The suspect left the scene before returning and threatening the victim again.
Officers believe the 328 bus service drove by while the incident was unfolding, and are appealing for any passengers or staff on the bus who has any information to get in contact.
A 20-year-old man was arrested in connection with the incident but has been released without charge.
Anyone with information is asked to contact police on 101, quoting crime reference 13190049883. Information can also be passed anonymously to independent charity Crimestoppers on 0800 555 111.