TCP/IP is actually a suite (grouping, stack,etc..) of protocols. HTTP is a protocol within the TCP/IP suite. Other protocols in this suite are TCP, IP, SMTP, FTP, etc.. There are TCP/IP protocols found spread across the OSI/TCP model.
As JorgeM said, HTTP is a higher-level protocol that runs on top of TCP/IP. TCP/IP is mostly layer 2, and HTTP layer 3. IE, HTTP works with, but not in place of, TCP/IP. Anyone can write their own layer-3 protocol that works with TCP/IP - I write them all the time for specialized purposes, such as sending performance data from our 1000's of servers to our Hadoop database in the Amazon cloud. We need such a protocol in order to deal with a number of reliability issues related to the firewalls and load balancers in place between the networks.