Amsterdammer here. I was not present in the fighting but local sources have shared what happened.
In short, the Israeli hooligans including some off-duty IOF soldiers were attacking locals and stealing Palestinian flags from peoples windows. Also chanting about death to Arabs and a bunch of other racist shit.
Finally the local activists and mixed youth (including many many non-left) had enough and started taking them on physically because they were sick of the disrespect.
The cops arrest and beat these locals while protecting the Israelis. Meanwhile you've all seen the propaganda crying anti-semitism.
They literally brought it on themselves. Fuck them.