I don't want my iPhone app to be available for iPad. How can I limit this so my iPhone app can't be downloaded onto an iPad?
Do you mean you don't want your iPhone app to run on an iPad or you don't want to make a version for iPad?
I ask because all iPhone apps should work on the iPad, just as they are. They will appear as a little box inside the window and the user can scale it up or down.
This is generally good practice, the more devices that can run your app, the better.
You can also make a universal binary with separate iPhone and iPad target, which essentially provides one app for each device in the same package.