WordPress.com blogs are protected by the Akismet comment spam filter. Akismet is pretty good at catching spam, but it is always still learning.
You may receive spam comments, spam likes, or even spam likes on comments. There are steps you can take to resolve this. It’s worth noting that if you get a sudden spike of ‘spam’ comments or likes from a particular site or type of site, you may find others experiencing the same problem by checking out the WordPress.com forums. In this case, listing the usernames of the spammers can help staff to look into these accounts for suspicious activity.
If you are receiving comments that you believe are spam, and they are not being caught by the spam filter (Akismet), it is best to mark them as spam to give Akismet a chance to learn how to work better. You would want to make sure you have modified the comment settings so that you have to manually approve comments before they appear on your site. You do this by going to your Discussions Settings page – from your My Sites menu click on Settings, then Discussion. The section you want is titled ‘Before a comment appears’.
You can then also hold a comment in the moderation queue if it matches certain rules (such as how many links it contains, and whether any words match words you list in the comment moderation box).
It is also possible to prevent comments from certain users by adding rules to the comment blacklist. However by doing this these comments go straight to Trash and are not marked as spam, so Akismet will not have a chance to learn how to work better.
It isn’t possible to remove likes or prevent someone from liking posts, however you can turn Likes on or off for individual posts or pages. You would do this by clicking on ‘Sharing’ in your post/page editor settings menu, and checking or unchecking the relevant boxes.
Spam comment likes
With comment likes, you can manage these to some degree. Unlike post likes, comment likes are either enabled or disabled for your whole site. If you enable comment likes you can also add a users email, name or username to the Comment Blacklist which will prevent them from liking comments. This blacklist is located in the Discussion Settings page, near the bottom.
Blocking users from visiting your site
You cannot block people from visiting your site. Your only option in this case would be to change your site visibility settings to Private, however you would then need to invite people to be able to see your site.