Photo: RNZ / Samuel Rillstone
The prime minister has accused critics of the government's pay equity shake-up of "scaremongering" and levelling "gendered abuse".
But Labour says the coalition is "gaslighting" half the population.
A law change - pushed through under urgency last week - raised the threshold for workers to prove they have been poorly paid due to their gender.
It will save the government billions of dollars which would have otherwise been paid out in increased wages.
Addressing reporters on Monday afternoon, Luxon said the government's plan had been presented disingenuously by many of its opponents.
"I've seen Labour Party emails out saying that we're actually cutting pay for women. Nothing further from the truth.
"Equal pay remains, no change. Pay parity remains, no change. Collective bargaining remains, no change. Settlements that have already happened under pay equity, no change."
Luxon also objected to "gender-based abuse" being directed at female ministers, saying that was "utterly unacceptable".
"By all means, tackle the issue. Debate the substance and content of pay equity, but what we saw over the weekend was completely and utterly out of line."
Luxon pointed to a scathing opinion piece in the Sunday Star Times which used the c-word to refer to female ministers.
He also cited an image of Workplace Relations Minister Brooke van Velden dressed as a Nazi which was shared on Facebook by a Labour Party volunteer team.
Labour leader Chris Hipkins agreed it was "totally unacceptable" and had directed the party to put systems in place to prevent volunteers making the same mistake again.
"To be clear, it wasn't a Labour Party-originated post. It was something that a volunteer party member reposted to a Labour Party page.
"It shouldn't have happened. I understand it was removed very quickly, but they need better systems in place to make sure that it can't happen again."
He said the post crossed the line, but other commentary on the issue did not.
"I think some of the commentary, some of the columns that were written, show the raw emotion of the issue."
But he said the coalition was "gaslighting half the population," rejecting its claim the law change was about making sure pay equity was "transparent, accurate and fair".
"All of the government's excuses simply don't wash.
"This is about the government balancing its budget, and New Zealand women are being asked to pay the price."
Luxon told reporters he could not release the amount that was being saved because the information was "budget sensitive".
When it was pointed out to him the government was able to choose what information was budget sensitive, Luxon reiterated the "impact impact of these costs are budget sensitive".
Luxon disagreed with the consideration that people may feel anxious knowing their wages will no longer increase as expected, but be forced to wait another 10 days before finding out how much.
"It will be revealed at the budget when we're looking at the totality of our fiscal situation."
Hipkins said it was "manifestly unjust" for people to wait for clarity on Budget Day.
"I cannot see, now that they've passed the law change, I can not see how it's still budget sensitive.
"I think being up front with how much they've saved about that, I can't see how that's still budget sensitive."
Luxon claimed there was "scaremongering" going on, and reporting on the issue had been "disingenuous".
"You're mixing up concepts around equal pay, pay parity. We're talking about pay equity here, not bargaining right," said Luxon.
Hipkins said the prime minister was the one who did not understand the difference.
"When we're talking about pay equity, we're talking about work of equal value not work that is the same.
"It's very important to understand that."
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
