One of the girls tripped over while running away from the masked men and injured her head and scraped her leg on the road, Fairfax reported.
"They stood and laughed at me," she said.
The men reportedly backed off after the girls threatened to report them to police. They did so once they arrived at one of the girl's homes and told her mother.
The girls said they did not have far to walk from the party and didn't want to spend money on a taxi so had decided to walk home.
"We've never had problems before," one of the victims said.
"It has put me off walking. I will get a taxi next time."
New Zealand is in the midst of a "creepy clown" epidemic where people are dressing as clowns to scare others. It had already hit the US and Australia.
Last week in Dunedin, a clown wielding an axe banged on a house door, terrifying the teenage occupant. The clown later returned with more people dressed as clowns, one holding a knife, before they ran off.
Earlier, a 22-year-old in Dunedin's student quarter was arrested after frightening students in Castle St dressed as a clown.
And earlier this month, a man wearing a clown mask slashed several tyres in Timaru.
In Hamilton, a 22-year-old woman was attacked by two men dressed as clowns in the early hours of October 9.
Several costume shops nationwide have pulled clown costumes because of the epidemic.