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.