I need to trigger a notification email to all the users who got created via rest API in JSD ? Could you please let me know is it possible to achieve this.?
While you can run a scripted listener on "User Created Event" I don't think there is anything in that event or in the user object that can tell you whether or not the creation was done via the REST API, or via the UI, or via some other integration.
The only way would be to create your own REST Endpoint (different than the built-in ones) and use that endpoint for your REST integration so that you can trigger those emails.