Criminals are using sex scams to blackmail international students, or lure them to isolated locations to rob them, Counties Manukau police say.
The crimes have been trending in south Auckland and police said students needed to know about the scams.
Inspector Nga-Wati Chaplow said South Asian males were being targeted for extortion.
"Relationships are developed over social media, promises are made. These victims expose themselves at the request of the female party and the blackmail goes from there," he said.
Inspector Chaplow said sex was also being used to trick Indian students into going to places where they could be robbed.
"There are websites where liaisons are arranged in the community. The liaison is a front so the males become victims of robbery."
Inspector Chaplow said police did not have figures about the scale of the problem, but there had a been a trend in the area.
The warning comes after Indian community leaders said Indian students were running into trouble in New Zealand, because they were not getting enough support from their tertiary institutions.
A director of the Sahaayta counselling service for ethnic minority groups in Manukau City, Sucharita Varma, said many Indian students did not understand their rights or what was legal in New Zealand, and the criminals were exploiting that ignorance.
"We are actually having to educate them, saying they've not done anything illegal," she said.
Students turning to sex work to support themselves
Meanwhile members of Auckland's Indian community told RNZ some Indian students were turning to sex work because they could not find other employment.
New Zealand Prostitutes' Collective national coordinator Catherine Healy said students from a variety of countries were working in New Zealand's sex industry, but there were not many of them.
Ms Healy said students who had spoken to the collective said they were comfortable with the work, though they would not do it in their own country.
However, she said the women were vulnerable because immigration law forbids foreign students from working in the sex industry.
That meant they feared deportation if their work was discovered and were less likely to complain about mistreatment or exploitation.
Ms Healy said the law was created to prevent trafficking of sex workers, but it should be changed.