You can't run webplayer builds on smartphones (you shouldn't use the webplayer at all, since it'll be discontinued in 2016)!
You can however export your game as an Xcode project for iOS.
There is also the option of exporting your game as a WebGL application.
The problem here being that
A.) The build will detect mobile browsers and refuse to start * and
B.) The performance will not be good. (expect <10fps)
You should however be able to add native iOS code to your project and run the rest of your phonegap app in a UIWebView.
-- more on the WebGL solution --
I tested a WebGL build in the FirefoxOS Emulator. It worked, but I can not tell you anything about the performance on the actual smartphone or if it works with iOS.
You should be able to remove this somewhere in a .js file.
OK - I tested the same build on my Xperia Z3 compact running the latest Version of Chrome for Android. While it did work, the framerate was very poor.
If your scene is not to complex and you don't mind low end smartphone users suffering through an unplesent experience, you could to it.
BUT YOU SHOULDN'T!
I still can't say anything for iOS, but since they added support for WebGL in Safari, I assume it will work to.
*If you want to remove the annoying popup you get,
just remove the lines 57 to 61 in the
/Release/UnityConfig.js-file in your WebGL build.