Go to Settings>General>Accessibility>Reduce Motion
Apples own website explains this in more detail:
iOS 7 uses a parallax effect to create the perception of depth on your Home screen and elsewhere. When this feature is on, you may notice that your:
Wallpaper, icons, and alerts shift slightly as you move your phone.
When setting a wallpaper in Settings > Wallpapers & Brightness, the photo or image will be slightly zoomed and cannot be scaled to fit to the screen.
You can change this behavior by enabling Settings > General > Accessibility > Reduce Motion.
Note: If zoomed, you will need to rescale your wallpaper to fit to the screen.