Yes. You can do that by using CIDR blocks of IP addresses, BUT I strongly recommend that you do not waste your time with doing that. BPS Pro has your site completely protected so the only reason I can think of to block entire countries would be because your Bandwidth is limited. These days most hosting comes with unlimited Bandwidth. See this forum topic for several months of research we did on blocking IP address and by country and using CIDR IP blocks: http://forum.ait-pro.com/forums/topic/buddypress-spam-registration-buddypress-anti-spam-registration/ The end result of all that research was we created JTC Anti-Spam|Anti-Hacker and abandoned trying to block millions of IP addresses since we discovered it is not really effective, time consuming and frankly a very dumb approach. 😉
If you do decide to mess around with this then this site: http://www.ipdeny.com/ipblocks/ has agregrated CIDR IP Blocks for countries.