Need your help! someone trying to Neg SEO me?

I own a site which is ranking good (since a week ago) for tough spanish kws. actually it is 1st spot for many of them.
Today I checked my stats and I found out that I got lot of traffic from a paid for surf website which I didnt pay for.
The site has adsense, maybe a competitor wants me to lose that account? Can this hurt my SERPs?

any input is apreciated!

block the traffic by the referral, and that should get rid of the paid to surf visitors. PM me and I can do this for you

Google will not penalize you for what another can do to you. If you are seriously concerned you can disclaim the links through WBT.