You may have noticed that iPhoto launches automatically when you connect your iPhone to your Mac. iPhoto started launched on my Mac even though my iPhoto settings didn’t enable this. It turns out you need to change your settings in the Image Capture app if iPhoto (or Aperture, as the case may be) has the option disabled in its settings.
The key is in the panel in the bottom left of the Image Capture window which you may need to expand by clicking on the little icon in that corner.
That should fix it for you.