didn't work on my router.
it should be like this:
That's a misunderstanding. The OP wanted to block PPTP to be transited
by his Mikrotik, and that rule works for that task.
Your rule blocks incoming GRE connections to your Mikrotik itself
, which is a different task (and to block PPTP connections to your Mikrotik itself, not enabling /interface pptp-server server
is sufficient, you don't need any rule for that).
In general blocking GRE kills not only PPTP but also other protocols using GRE, which may be fine for the OP's purposes but in general it is a bad idea.