Hi Sameer,
If you're using an 'ESB Service' node, an action handler is automatically added that references this class you're missing. However, this class is not part of the jBPM distribution; it's part of the JBoss ESB distribution (e.g. look at this class in the anonymous SVN repo for JBoss ESB: http://anonsvn.jboss.org/repos/labs/labs/jbossesb/tags/JBESB_4_8/product/services/jbpm/src/main/java/org/jboss/soa/esb/services/jbpm/actionhandlers/EsbActionHandler.java).
So you'll have to include a JBoss ESB jar on your classpath to remove the exception - and at least be able to deploy your process.
Regards,
Maurice