Police are urging people to stay alert after reports from several districts around the country of people receiving a scam call from someone claiming to be an officer.
In a statement, police said the person claiming to be a police officer will say they are from a certain department and tell the person they have been a victim of fraud or a scam.
They will then attempt to get further financial information.
Police said some people have even been told to go to the bank and get money out as evidence of the scam.
"This is a scam - no legitimate police officer will ever ask you to hand over money, for any reason," a police spokesperson said.
"If you want to establish if the officer is genuine, ask for the officer's full details.
"Hang up, contact 105 and request someone to check for you."
Police said older people are being targeted.
"Since early August, Police have had several instances of this being reported and we have made arrests in Auckland and Wellington.
"Three people are currently before the courts in relation to scamming vulnerable people in the Auckland and Wellington districts."
One of the arrested is a 26-year-old from the United Kingdom and has been convicted of scamming victims out of more than $330,000.
"People will need to be vigilant because enquiries into reports of such scams are ongoing.
"New Zealand Police will also never contact people seeking their banking details, card numbers, PIN, or passwords."
Police said there were some instances where officers would contact a person - but they would never ask for someone to take money out from the bank.