Police are being accused of getting violent at a protest outside Wellington's Westpac stadium.

Activists have taken issue with a New Zealand Defence Industry Association conference.

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At one point, about 50 police officers swooped in to move protesters out of the way so a bus load of delegates could get in.

Protester Stacey Rose said he felt very unsafe.

"Police were getting extremely violent at that point in time and we were getting pushed, shoved and some people getting kicked and punched."

While protester, Dan Kelly said he's never experienced that sort of violence before.

"It came out in a very aggressive way completely contrary to the peaceful protest that we were demonstrating, so yeah, it was shocking."

Police say officers acted professionally and handled the situation appropriately.

NZDIA deputy chair Andrew Ford said he respects their rights to free speech and protest.

"I think it over-steps the mark a little when you're willing to take action that prevents others from exercising their freedoms."