Yes
A quick and dirty way, if you know the destination ip addresses you’re trying to deny access to, is to use firewall filters +/- address lists. e.g /ip firewall filter add chain=output src-address=192.168.1.0/24 dst-address=69.63.184.142 action=drop
Otherwise, you will need to setup web proxy: http://www.mikrotik.com/testdocs/ros/3.0/pnp/proxy_content.php#.4