If you want to restrict them to only view the computers in your custom organizational view, you'll want to edit the security role. Find the custom security role, edit it, then select Security Role Manager Console. Change the drop-down to Resources, then click the Edit pencil. Expand the custom organizational view you created and place a checkmark next to the Organizational Group(s) that you want them to view. Then expand the Default organizational view and uncheck Default > All Resources > Assets > Network Resources > Computers. If you synchronized with Active Directory, uncheck everything in the Active Directory view as well.
These steps ensure that not only do they have a view where they can see computers, but they won't have access to wander in the console (such as Manage > Computers) to perform tasks on computers for which they are not authorized.
Hope this helps. And welcome to Symantec Connect!