Literally illegal to call for less immigration.
Not at all.
In that specific hate-inciting speech Geert Wilders was calling for fewer Moroccans. And this is primarily directed towards Dutch people with a Moroccan background who've already live in the Netherlands for decades or are second-generation immigrants. There is virtually no immigration from Morocco, in 2015 approximately 1% of the immigrants arriving in The Netherlands was Moroccan [1].
[1] https://www.cbs.nl/nl-nl/publicatie/2016/47/jaarrapport-inte...