You wish to block Google Image search results using the Symantec Web Gateway.
It is not possible to
block embedded images in a Google Image search using an SWG content filtering rule.
This is because the images are downloaded directly from Google and not the site itself. As the SWG content filtering engine blocks sites based on a database of known URL’s it has no reason to block this content. However, any attempt to connect to the website serving the images is blocked correctly. This applies to both HTTP and SSL traffic.
Google suggest using Google SafeSearch functionality to block inappropriate embedded images from being displayed: