National's police spokesperson said the "assault" of anti-transgender activist Posie Parker on Saturday represents a "failure" by police.
"If you have someone that is trying to exercise their freedom of speech and doing a public event like that and they're assaulted, then there's been a failure," Mark Mitchell said.
"It sends a terrible message. Because in this country, we should really defend and protect our freedom of speech. Whether you agree with the person and what they are saying is irrelevant. There should have been better protection to ensure there wasn't that type of violence and assault."
He said if police are present and know the event is occurring, "they should have been planning for that and because someone was actually assaulted at it, it means they have failed in making sure that event could have actually gone forward".
Police Minister Ginny Andersen told Newshub it is up to police to "assess any given risk on that time or that occasion and to respond accordingly."
Asked if she believed police responded appropriately, Andersen said: "I am confident that the risk assessment undertaken by police was responded to by staffing the event and making sure there was enough back-up in place should it be needed."
Parker, who founded the anti-transgender rights group Standing for Women, was at Auckland's Albert Park on Saturday to speak, but had to be escorted away after having red juice dumped onto her by a pro-transgender activist.
Auckland City District Commander Inspector Grant Tetzlaff on Monday told Newshub that police were at the event on Saturday monitoring it and a counter-protest.
He said it is the "role of Police at events like these is to keep the peace, and uphold the law, while recognising the lawful right to protest".
"As soon as it became clear there was a potential safety risk to the Albert Park event speaker, she was escorted from the area by police staff," he said.
"Police did not make any arrests on the day, but we continue to make enquiries into Saturday's events.
He said police are "reviewing CCTV footage and video of the protest posted to social media to determine if any other offending may have occurred."
Mitchell on Tuesday said he hopes police are reviewing what happened on Saturday and are "clear about how they are going to deal with future events" to ensure people's safety.
He said police should have had intelligence "to inform them in terms of what they had to do".
"My expectation is that the police do all that they can and use every power that they have to make sure that someone can go out in public and actually speak about an issue and that their safety can be assured."
He said pouring the red liquid on Parker was an assault.
"Could you imagine if any of us walked up to someone else and started pouring fluid, by the way, she would have had no idea what it was, that is traumatic. We shouldn't accept it and it is absolutely an assault."
A reporter asked if Prime Minister should make sure police prosecute the individual who did that.
"Absolutely," Mitchell said. "My expectation is that police obviously investigate it. They will make their own decisions in terms of, how they deal with it, whether it's a prosecution, whether it's an alternative action, I don't know."
"It's very obvious, it was all caught on tape. so there's plenty of evidence."
When he was questioned on why he thought the Prime Minister should make the police prosecute, given the police are independent, Mitchell clarified he had misunderstood the question and it's not appropriate for the Prime Minister or Police Minister to direct police.
"My expectation is the police have got a lot of evidence there and they should be looking seriously at what their options are and their action."
He said what police do is an "operational issue".
"I would expect them to have all the evidence that they have in front of them and then take a decision on what action is going to be taken.
"In my view, in this country when there is an obvious assault like that that takes place, the expectation is the police are the one agency that have got the powers to be able to take action on it and my expectation is that they do take some action."
Stuart Nash resigned as Police Minister two weeks ago after admitting to phoning the Police Commissioner about a court judgement.
Mitchell said he isn't the minister.
Prime Minister Chris Hipkins wouldn't discuss police's response as he didn't "want to get into the territory of questioning police operational decisions".
"My expectation is that the police's job is to keep the community safe. That includes people who we might disagree with. Having said that I don't want to comment on any specific instances because those are ultimately operational."
While the protest against Parker was mostly peaceful, video does show scuffles in the crowd and Parker being pushed and squeezed as she was walked out of the park. Among those in attendance were far-right figures.
Auckland Pride, one of the main supporters of the counter-protest against Parker, said thousands of Aucklanders stood "in solidarity with trans communities [and] sent a clear message to Parker that intolerance will not be tolerated here".
"Auckland Pride unequivocally stands by peaceful protest as a means of counter protest, and does not endorse any physical violence, regardless of the extent of injury caused."
It said the reason for her departure was that the noise from counter-protesters was "too loud to overcome".
"We also reject that there was any further physical threat from our community towards Parker. This is a baseless rumour that is being perpetrated by those who feel defeated by the events of today."
Greens co-leader Marama Davidson was hit by a motorcycle following the event.
