Google wants to translate my non-English site [SERP drop]

Hello,

For some time there is "Translate This Page" next to my website url. The thing is that my site is Polish and there is no English content there. I've noticed quite a big SERP drop and I suspect this is becouse of this translating issue.

Of course I have <html lang="**-**"> and location for Poland set in GWT.

I am even willing to pay for someone how can help me fix this issue and get my SERPS back.

Thank you.