How to prevent user to access the SharePoint Apps on the site collection if user dont have access to Site Collection?

Question

I have a SharePoint Online user USER-1 and Site Collection as Site-1.

Scenario:

Now, USER-1 does not have permission to access the Site-1, but an app installed in Site-1 is accessible to the USER-1 if direct url to the app is provided to the USER-1.

I want to prevent this accessibility.

Any suggestion is most welcome.

Its a SharePoint Hosted App.

The permission of the app is as follow.