Help needed in creating a policy to block usb devices and cdroms for unmanaged clients?

HI all,

I have 12.1.2 SEPM and clients in my environment. i have few unmanaged clients too in our environment. can i just block usb devices and cdroms with out making them managed and installing all  features on them. I think we can do that by  importing policy file, could u guys help me out on this please

Regards,

Anoop Jeevan.