One source Google uses to generate snippets is the Open Directory Project. You can direct us not to use this as a source by adding a meta tag to your pages.
To prevent all search engines (that support the meta tag) from using this information for the page's description, use the following:
<meta name="robots" content="NOODP">
To specifically prevent Google from using this information for a page's description, use the following:
<meta name="googlebot" content="NOODP">
If you use the robots meta tag for other directives, you can combine those. For instance:
<meta name="googlebot" content="NOODP, nofollow">
Note that once you add this meta tag to your pages, it may take some time for changes to your snippets to appear in the index.
Source: https://support.google.com/webmasters/answer/35624?hl=en
