Hi CM,
Web Services API is enabled by deafult howver but u need to configure and give access setting to it.
The Incident Reporting and Update API is a Web service that allows client applications to read and update incident data stored in a Symantec Data Loss Prevention deployment. The API is available with Symantec Data Loss Prevention version 11.6 and later.
http://www.symantec.com/business/support/index?page=content&id=HOWTO41496