The message was scrawled in chalk on the footpath outside the Al Noor (Masjid An-Nur) mosque in Christchurch on Saturday and read 'Islam is right about women'.
The cryptic message was left while worshippers were inside at prayer and was being investigated by the police.
It came just days after the Royal Commission reported its findings on the mosque attacks, including a recommendation for harsher penalties for hate speech.
Canterbury district commander John Price said it was being taken very seriously.
"Any messaging that is an undertone that is not right for us in New Zealand is concerning no matter what time that occurs. So, we take these matters seriously, whether or not it be on the back of the Royal Commission of Inquiry or not."
In response, police officers would be stationed inside and outside Al Noor.
"We've got presence in and around the mosque and we'll continue to do so to provide any reassurance. Visible policing does enable a confidence and trust by our community."
Al Noor worshipper, Mirwais Waziri, who was injured in the attacks, said unfortunately there had been an increase in hate speech directed towards Muslims in Christchurch ever since 15 March.
"Whenever my wife goes somewhere in the markets, some of these racist people, they just use some words and she just ignores them. I hope people understand that we are New Zealanders. We live in New Zealand, and we live peacefully and we have a beautiful religion."
He said 15 March 2019 had shown us that such abuse needed to be documented and taken seriously.
"It's not a joke. It's a serious matter, discrimination of a person and a religious person. We live in a free world and especially democracy.
"New Zealand has different rights. Everyone lives in this country, and everybody's rights should be protected."
An expert on Far Right groups, professor Paul Spoonley, said the same statement left outside Al Noor, had appeared in various forms around the world and was designed by these groups to stoke hatred towards Islam.
"It appears internationally to be a way of trolling, what the right call the woke left. And so it's designed to draw attention to the way in which Islam is supposed to suppress women, but in a sense, they flip it around. So it appears to be in support of the way in which Islam treats women. But of course the intention is quite the reverse."
However Spoonley would not class the words as hate speech.
"It's designed to avoid being defined as hate speech. And so it appears to be in support of Islam and not critical or not inflammatory or racist, but in fact, it is."
Spoonley said far right groups now stretched around the world as online communities.
They were hard to track, as those involved mostly remained anonymous.
