The Google Webmaster Central blog has a post on “dealing” with low quality backlinks. In that post, Google basically explains that incoming links is “just one of many” ranking factors. That being the case, Google says if you have bad quality incoming links, “don’t fret” it and focus on things you can control, like your content.
Google does offer advice, such as asking the source of the link to remove your site from their page. If that doesn’t work, there is not much you can do. There is currently no tool in Webmaster Tools to communicate to Google to ignore certain links from sources on the Internet.
Google explains that over time they remove low quality sources from their index, so these links should not hurt you over time. Google recommends you report low quality sites in their spam report tool or paid link report.