how to prevent iPad "compatibility mode" app

In our iPhone app, we set UIDeviceFamily to 1 for iPhone only, but our app still appears as compatible with iPad in the app store listing, and I can install it on my iPad. I understand that this is running in "compatibility mode". Due to the expense, our business people don't want us to support iPads quite yet. So, how do I prevent our app from installing on iPads?

I see that other apps don't appear as compatible with iPad, and I can't even find them in the store on my iPad. (example: WhatsApp Messenger ) I assume this is achieved through UIRequiredDeviceCapabilities that are specifying capabilities that are available on iPhone but not iPad. Is that accurate?