How do you cite an image from Google Images? Simple. You do not.
Google Images is a search for images. The search does not own images. Care must be taken to find the original owner of the image. In Google Images, there is a link to the right of the image that says "Visit Page." Sometimes this link goes to a page that does not identify origination, creator, name or owner of image. If there isn't enough information to cite an image, locate a more credible image.
More simply, trying to cite an image found on Google Images is the same as citing a Google for a website located using the Google search. Google finds items but does not own, have authority, create or hold the resource. It simply finds them unless the URL contains Google.com or the copyright is affiliated clearly with Google.
Have an image that needs identification? The reverse image search on Tineye.com sometimes helps find an original owner of an image. There are often many to sort through. Use criteria used to locate credible internet information to narrow down leads to original source.
The best strategy is to find and use credible images with licenses that allow their use. Remember, though a site or license does not require attribution or citation, a Professor likely will. Image sites to use instead of Google Images: