It was shortly after midnight on Saturday 20, at the Keystones pub on Monkbar.
North Yorkshire Police say a woman, thought to be celebrating her 21st birthday, assaulted a member of staff in the pub beer garden.
The woman is described as white, slim, five feet six to eight inches in height, with long wavy dark hair in which she had put blue/silver streamers. She was wearing a white top with a dark cardigan, a birthday badge, patterned skirt, black tights, and dark coloured boots. She wore a black handbag over her shoulder and had a black Labrador or similar breed dog on a lead.
She was with a man of similar age and an older couple.
The young man is described as white, very slim, over six feet tall, with thick bushy brown hair. He was wearing a light blue shirt over a dark t-shirt, dark jeans, and black trainers with white trim. He was also carrying a distinctive red and white patterned rucksack.
The older woman in the group is described as white, in her late 40s, large build, five feet six to eight inches in height, with short hair in a loose dark bob. She was wearing a long sleeved dark coloured dress, black tights, and dark coloured court shoes, and was carrying several bags.
The older man in the group is described as white, in his late 40s, heavy build with a distinctive rotund belly, approximately five feet, ten inches in height, with dark receding hair. He was wearing a light coloured short sleeved shirt, loose fitting dark trousers, and a dark coloured jacket with a biker-style collar.
A police spokesperson said: "Officers would like to speak to the persons described above regarding this matter and are appealing for assistance to identify them.
Anyone with information that could assist the investigation should contact North Yorkshire Police on 101, select option 1. You can also email [email protected]
If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.