​@xNourahx Just to be clear on your issue, are the users initiating RDP sessions directly from the Resource Brokers or are they initiating RDP from Managed System Proxy sessions. 

Password Safe Cloud relies on Resource Brokers to proxy the RDP sessions. So, we cannot restrict RDP protocol on Resource Brokers. As a best practice, except Server Admins, PAM Admins, functional account, no other users should have direct access to RB servers.