Translation isn’t possible.

On the page that displays when you don’t have access since it’s blocked by the security settings, only the title is translatable.

This string isn’t:
“Your request looks suspiciously similar to automated requests from spam posting software or it has been denied by a security policy configured by the website administrator.

If you believe you should be able to perform this request, please let us know.”

At least, I’m unable to find it in the .pot file. Which is extremely strange to have a translated title and then an English text. :/