Ten people have been arrested following the protest that took place at the weapons expo in Palmerston North yesterday.
Two were arrested for assaulting police while the rest were arrested for disorder and obstruction.
Police say protesters outside the expo venue disrupted local traffic and the public.
"Police were pleased with the behavior of protesters involved in the march from the square. However, we are disappointed with the behavior of some outside the venue who acted in a way that created safety issues."
Speaking before the event, Peace Action Manawatu spokesperson Te Ao Pritchard said the group planned to protest in a number of ways..
"Our three groups are planning a range of activities over the days of the 'weapons expo' including educational films and speaking events, creative displays, a family-friendly peace march, a multi-faith gathering and church service in addition to non-violent direct actions."
Protesters had blocked buses carrying defence personnel to the venue.
As a result, the police have blocked roads around the venue and put black sheeting in place to avoid disruption for people attending the event.