It may also help to change the brake pads, here you can find more information.
Noise from disc brake pads can never be completely eliminated for purely physical reasons. Note that in wet road conditions your disc brakes will always be noisy.
All hydraulic disc brakes need to be "bedded". This helps the brake pads to develop their full braking power and can reduce the noise when braking. In this article, we explain how to do it.
We also recommend checking for brake pad wear and replacing them, if the noise can not be eliminated. Read more here.