Bitcoin P2P transactions cannot be banned. There is no mechanism with which to detect that a Bitcoin transaction has been made, let alone detect who has made a transaction[1], since you can broadcast a transaction with a completely different IP address outside of Belarus' authority.
Maybe he wants to ban exchanges or off-ramps or the equivalent.
[1]: Outside of the very obvious and standard blockchain analysis services, but even these require a trail to already have been made that goes through a KYC service.
The idea is not to ban Bitcoin P2P transactions but to deem anyone found participating in such activities a criminal who may be prosecuted and "legally" deprived of their belongings, including cryptocurrency holdings. Authoritarian government merely wants more leverage to control its citizens, which is why it keeps introducing such ridiculous laws that can't be realistically enforced at a large scale, but that can be used against opposition and other "wrong" people. Needless to say, "a high cybercrime rate" is just an excuse to introduce more prohibitions.
Belarusians can broadcast their transactions using a full node, or with any pushtx-style webpage while connected over a VPN or Tor, to obfuscate the location where the transactions were made. And there's no way for authorities to reliably track the location of the user with this method because all that remains in APIs are a bunch of node IP addresses and (at worst) client IP addresses that have visited a particular webpage, if they decide to take their internet surveillance that far.
Not that I think they will, as this seems to be a very incompetent government as far as technology is concerned.