Google translation:
hi all, I am constantly getting abuse from some visitors to your blog, such as racial predbezhdeniya or simply rude mate tell me how can I block or file a complaint and where on such individuals.
Thanks in advance. Marina.
Hellow Marina, you can have comments held in moderation by entering the person's username, email address and website if they provide one at settings > discussion in the blacklist box. That will not entirely block them, but it can help to keep the comments from showing up on your site.
I would also suggest setting comment moderation on so that all comments have to be approved by you. Hopefully they will get tired of not having their comments show up and go away.
You can also read through this: http://en.wordpress.com/abuse/ . Do realize that if they commenters are not hosted at wordpress.COM, there is little wordpress.COM can do to stop them.