The unnatural links to site – impacts links notification is very common. This is a manual action that is put in place by Google. You can verify if you have this manual action by logging into webmaster tools.
A website will generally get this notification if they have poor links pointing at their website. However, if they have a very large amount of bad links pointing at their website they will get a worse notification known as unnatural links to site – impacts site.
In general, this penalty only hurts rankings for certain links and certain URLs, and it does not hurt the entire website. This is much different than the impacts site notification, which penalizes the entire website.
Google does recommend that you deal with this notification by removing bad links.
Watch a video on this Google webmaster tools notification.