To block images from showing up in Googles search results, all that is needed is a file called robots.txt. This file is used to instruct the search engines about which parts you don't want them to crawl. It can also be used to disallow specific search engines from crawling your site, while allowing the ones that you care about. Be careful however, not all robots will respect the rules in your robots.txt file.
If you just want to disallow search engines from crawling your images directory, then use something like below.
User-agent: * Disallow: /images/
The asterisks is used to match all search engines. If you only want your images removed from Google, than you may want to try something like below.
User-agent: Googlebot-Image Disallow: /
That would disallow Google's image crawler access to your entire site. Other search engines may use similar user-agent strings for their image crawler. But the first option is likely the easiest.
Removing images from Google
Keep in mind that there might go some time before Google will have all your images removed. And removing all of your images might not be a good idea, even images can bring in some visitors. Unless your images is part of your layout, you likely want to reconsider whether you want them removed.