The week-long protest at Parliament is "representative of an immense amount of frustration" with the Government's COVID-19 response, according to Christopher Luxon.
But the National Party leader will not engage with the protesters because "we respect people's right to protest but we expect them to do it within the rules and that's not been happening".
Luxon made the remarks on the eighth consecutive day of protesting on Parliament's grounds by groups opposed to various COVID-19 restrictions, most notably vaccination mandates imposed on a range of professions.
Prime Minister Jacinda Ardern has so far refused to engage with the protesters, who have camped outside Parliament in tents and blocked traffic in the surrounding area of central Wellington.
Police last week arrested more than 120 protesters after House Speaker Trevor Mallard issued a trespass notice. But a core group remained over the weekend, despite the Speaker's controversial attempts at dispersing them with sprinklers and loud music.
"I think the challenge for us, looking at that protest out there, is there's a wide range of groups. They range of white supremacists to Māori separatists and everything in between. I think the challenge has been there's no defined leadership there to engage with," Luxon told reporters on Tuesday.
"At the same time, we've had a lot of anti-social, abusive behaviour and it's very difficult to engage with that group.
"What I would say though, is that it's representative of an immense amount of frustration that sits in the country around where we are going with our Omicron plan and why we don't have clarity going forward."
Luxon said he would not support his MPs engaging with the protesters.
"No, as you know, in the National Party we're pro-vaccination, pro-boosters, and that's been our position as a party, and so everybody's been very clear about that.
"We respect people's right to protest but we expect them to do it within the rules and that's not been happening. We're a party of law and order and so at this point we wouldn't be doing that."
But Luxon acknowledged some of their frustrations.
"There are people who have done the right thing. They've gone off and got triple-boosted and they are incredibly frustrated with the fact that they don't see clarity now going forward. We had great clarity in 2020 and we've lost that in 2021 and 2022.
"Our answer is we should have a conversation around the criteria and triggers by which mandates will ultimately get released.
"We see that around the world. When Omicron becomes endemic, the relevancy of mandates diminishes over time. What you've got to get really clear on is the triggers and the criteria which will then ultimately determine the timeframe for that.
"I'd be very happy to engage with the Government on that."
Ardern said on Monday she would not engage with the protesters because with Omicron cases growing in the community - more than 800 cases were registered that day - COVID-19 restrictions were important.
"Let's be really clear: from what I've seen in writing today from those who continue to occupy the forecourt of Parliament and cause an inability for those in Wellington to currently move around freely, their request and demands of the New Zealand people is that all public health measures are removed," she said at her post-Cabinet press conference.
"That means at the very point where we're seeing an increase in cases and an increase in risk to the public health and wellbeing of New Zealand, they want to see removed the very measures that have kept us safe, well, and alive. You'll forgive me if I take a very strong view on that suggestion.
"I very clearly have a view on the protest and the way that they've conducted their protest, because it's moved beyond sharing a view to intimidation and harassment of the people around central Wellington. That cannot be tolerated."
Former National MP Matt King, who lost his Northland seat to Labour's Willow-Jean Prime at the last election, vowed to join the protest, because he agreed that mandated vaccination should come to an end.
"I believe we can get most if not all of them off if they are given a rock-solid guarantee that they will remove the mandates on a certain date," he told AM on Monday.
But Ardern, speaking to AM after King, said she could not engage with protesters who have threatened politicians and caused local disruption.
"I'm going to push back on the sense here that this is a group that we're seeing wanting to engage in political dialogue. We've seen some horrific behaviour down there and I'm not going to legitimise it."
Wellington District Commander Corrie Parnell said on Monday evening despite the Parliament grounds remaining officially closed, a large number of tents and marquees were still up, "in breach of the standard conditions for all protests and demonstrations".
"Police continue to have a large presence at Parliament and have had productive talks with some protest groups. Attempts to connect with other factions are ongoing."
The protesters were provided a safe parking facility by Sky Stadium on Monday evening, but the offer was largely ignored. Protesters' vehicles remain parked all around the Parliament buildings and the central railway station.