Restricting app installations from AppStore only to users with iPhone 5/5s/5c

I have found this Important note:

The store rejects a binary that supports only armv7s. If armv7s is included in the Valid Architectures list, armv7 must also be included.

From App Distribution Guide.

Specifying armv7s in your Info.plist's UIRequiredDeviceCapabilities should be enough as it means it requires compatibility with the armv7s instruction set, which in turn is compatible with arm64 and any future Ax processor.

Also it would be interesting to know why you need to restrict your App in the first place.

Up to date Apple capabilities list here. There is no official way to cut requirement between iPhone 4 and 5 besides armv7s.

Also there is a new good reason to require iPhone 5+ devices: WatchKit apps that have no meaningful iPhone parent app. For instance a game for Apple Watch. One should prevent devices that can not possibly work with the watch from downloading the App.