Have you tried with the same machine or system connected to another network? Have you tried with another machine on the same network? From your current description (which may not be accurate) the most probable explanation is that the ping is blocked by your ISP.
My results form ICMP:
# ping google.com
PING google.com (184.108.40.206) 56(84) bytes of data.
64 bytes from fra07s27-in-f1.1e100.net (220.127.116.11): icmp_seq=1 ttl=57 time=12.8 ms
64 bytes from fra07s27-in-f1.1e100.net (18.104.22.168): icmp_seq=2 ttl=57 time=15.8 ms
64 bytes from fra07s27-in-f1.1e100.net (22.214.171.124): icmp_seq=3 ttl=57 time=14.3 ms
--- google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 3518ms
rtt min/avg/max/mdev = 12.861/14.365/15.898/1.240 ms
And my results for HTTP:
# curl -I http://www.google.com
HTTP/1.1 302 Found
Content-Type: text/html; charset=UTF-8
Date: Sat, 03 Jan 2015 14:10:39 GMT
Your firewall wouldn't normally block you from pinging another machine using the IPv4 ICMP echo request.