Hi, please how can I block a specific URL and not the entire website?

ie, block:
https://cdn.pixabay.com/photo/2015/04/2 ... 60_720.jpg

But permit:
https://cdn.pixabay.com

How can I do this with Regexp rules? Or is there a better way to do it? (Need to block +10.000 specific URLs)

Maybe you can try , see more details here https://wiki.mikrotik.com/wiki/Manual:I ... all/Filter

You can't. With tls-host, you can match only cdn.pixabay.com, the rest is encrypted.