There is no specific way to block the URL with the usual ACL on the Cisco router, but you can do a work around and mark the packets for specific URL with some DSCP value, and then filter on that DSCP value in the ACL.
Steps are very simple:
1. create class map and match on specific url
2. create the policy map and under the specified class map set dscp value. Make sure that this dscp value is not used by other traffic, otherwise it may be dropped.
3. apply policy on the inbound interface.
4. create and apply ACL on the outbound interface in outbound direction that will deny packets with that dscp value.