Are there any legal regulations in the Netherlands about time when it's not allowed to play music loudly or do any works which produce a lot of noise? I'm asking specifically about campings and other recreation areas. What can I do if some guests are having a very loud party during the night?
Most campings will have specific rules about that, but it will vary per campsite. Enforcement too will differ per site, but generally they will try to keep all their guests happy so they will look for some compromise when there are complaints. That said, I've seen people being send away from a camping for being too noisy.
In general, if you are looking for quietness go for the smaller sites. Most people there will be looking for the same thing. And usually it's pretty clear what the 'target audience' is when looking up the website of a camping and/or reading a few reviews.
Legally, there are rules about excessive noise and causing disturbances, although those are not tied to a specific time. Besides law there may be local rules, but they very wildly and generally don't cover campsites. Either way, on a campsite go through the camp personnel first, the police will generally not show up to deal with complaints the camping should be able to deal with themselves.