Police said he struck at least three times with the violence escalating until he threatened his last victim with a machete.
No arrests have been made following the attacks, GayNZ.com reported.
Mr Newman said anyone using dating sites' hook-up apps should be cautious and aware of personal safety. He recommended app users take a friend or someone for company when meeting with a person for the first time.He also recommended meeting in public areas.
"It's important to plan ahead and be careful. Always tells a friend where you are going and who you are meeting up with, and ensure they have your contact details," he said.