Unfortunately I can't really give you an indepth answer about the deployment of military vehicles against civilians in the netherlands and its legal framework.

There's however a great article about the riots in the vondelstraat:

http://www.geschiedenis24.nl/andere-tijden/afleveringen/1999-2000/De-Vondelstraat.html

The mayor, prosecutor and head of the policeforces decided to ask the military to help them in the riots since the police forces were unable and unequipped to break the riots.

A call was made to the hotline of the ministery of domestic affairs. The next day a new meeting was held, with addition of the representative of the queen (head of the police force in the province) and commander of the anti riot police.

The army was send in with a couple of tanks. The commander decided before the use of tanks to inspect the squatters barricades himself (undercover). Apparently he looked so shabby that the squatters didn't recognize him, and thought he was one of their own. He helped to squatters set up their defenses but made sure there were some weak spots in their barricades. There was a lot of discussion about the military use and specifically if they were alowed to shoot at civilians. It doesn't really mention anything about the legal framework, ill try to do some more searches but Im at work atm. Im however unknown about any law which specifically prohibits the use of military forces against our own population.

Edit:

The government website (http://www.rijksoverheid.nl/onderwerpen/krijgsmacht/vraag-en-antwoord/wat-doet-het-nederlandse-leger.html) does give a bit more clarification. The three main tasks of the dutch armed forces are:

1. Defending the country and its allies.
2. To improve international stability
3. To help the local governments in upholding the law, emergencies.

The legal framework is de grondwet (constitution of the netherlands) article 97.