The incident happened on the walkway on Annesbrook Drive about 8am on May 11.
Police say the man is of a medium build, in his 20s to 30s, and has short dark hair and tanned skin.
He was wearing dark coloured clothing and drove a black van with a large, fluffy, black dog inside.
Anyone with information that could help in identifying the person is asked to contact police on 105 and quote file number 220512/3662.
Alternatively, information can be given anonymously via Crime Stoppers on 0800 555 111.