I found that Google introduced a new tool for Webmasters, "Disavow Links", that enables you to disavow links to your site. If you've been notified of a manual spam action based on "unnatural links" pointing to your site, this tool can help you address the issue. If you haven't gotten this notification, this tool generally isn't something you need to worry about."
Google says its engineers have been beta testing the new feature for weeks now, although there have been rumors of the impending new addition for months. The tool is now live, and you can find it by logging into your Webmaster Tools account and navigating to https://www.google.com/webmasters/tools/disavow-links-main