It seems that tomcat7 is not in the standard/epel repositories for centos6.5 yet.
[root@secure36 rfridman]# cat /etc/issue
CentOS release 6.5 (Final)
[root@secure36 rfridman]# yum search tomcat
Loaded plugins: fastestmirror, security
Loading mirror speeds from cached hostfile
* base: mirror.atlanticmetro.net
* epel: mirror.symnds.com
* extras: mirror.es.its.nyu.edu
* updates: mirror.cogentco.com
==================================================================== N/S Matched: tomcat =====================================================================
tomcatjss.noarch : JSSE implementation using JSS for Tomcat
apache-tomcat-apis.noarch : Tomcat Servlet and JSP APIs
jakarta-commons-collections-tomcat5.noarch : Jakarta Commons Collection dependency for Tomcat5
jakarta-commons-dbcp-tomcat5.noarch : DBCP dependency for Tomcat5
jakarta-commons-pool-tomcat5.x86_64 : Pool dependency for Tomcat5
jglobus-ssl-proxies-tomcat.noarch : Globus Java - SSL and proxy certificate support for Tomcat
tomcat-admin-webapps.noarch : The host-manager and manager web applications for Apache Tomcat
tomcat-docs-webapp.noarch : The docs web application for Apache Tomcat
tomcat-javadoc.noarch : Javadoc generated documentation for Apache Tomcat
tomcat-jsp-2.2-api.noarch : Apache Tomcat JSP API implementation classes
tomcat-jsvc.noarch : Apache jsvc wrapper for Apache Tomcat as separate service
tomcat-lib.noarch : Libraries needed to run the Tomcat Web container
tomcat-native.x86_64 : Tomcat native library
tomcat-servlet-3.0-api.noarch : Apache Tomcat Servlet API implementation classes
tomcat-webapps.noarch : The ROOT and examples web applications for Apache Tomcat
tomcat6.noarch : Apache Servlet/JSP Engine, RI for Servlet 2.5/JSP 2.1 API
tomcat6-admin-webapps.noarch : The host-manager and manager web applications for Apache Tomcat
tomcat6-docs-webapp.noarch : The docs web application for Apache Tomcat
tomcat6-javadoc.noarch : Javadoc generated documentation for Apache Tomcat
tomcat6-jsp-2.1-api.noarch : Apache Tomcat JSP API implementation classes
tomcat6-lib.noarch : Libraries needed to run the Tomcat Web container
tomcat6-servlet-2.5-api.noarch : Apache Tomcat Servlet API implementation classes
tomcat6-webapps.noarch : The ROOT and examples web applications for Apache Tomcat
glite-security-trustmanager-tomcat6.noarch : Java trustmanager interface supporting a GSI grid name space
tomcat.noarch : Apache Servlet/JSP Engine, RI for Servlet 3.0/JSP 2.2 API
tomcat-el-2.2-api.noarch : Expression Language v1.0 API
tomcat6-el-2.1-api.noarch : Expression Language v1.0 API
You should try to compile the tomcat7 from the source, or try to find the repository with tomcat7 included and add it to your cookbooks configuration.