That one is easy.
So the website you're trying to reach was censored by your Internet Service Provider using some DNS method. You're being redirected to some official statement telling you the website is bad for you.
What should you do ? Easy !!
- Use alternative websites when available (mirrors).
- Use alternative DNS servers.
Alternative DNS servers are DNS servers that are not controlled by your ISP and therefore not subject to the same censorhip.
In the case of ThePirateBay, Google DNS servers are not censoring the website. So you can actually switch to Google DNS servers and regain access to the website.
How to do that ?
Detailed instructions are right here https://code.google.com/intl/en/speed/public-dns/docs/using.html
Once you did that, you should be able to access the censored website again. Now if that didn't work ... you should head over to the second section DNS and IP Censorship because you're probably being IP censored too.