Well, let says you already have Google Plus (Google+) account now, then after you have added a few people you don't know yet, or some of friends to your account you found a few of them are not friendly with you even they're so annoying you. I think the interesting about Google+ is that there's one feature named "Circle", which allows you to manage all your friends whom you wanna share, and whom you don't, this feature just make your Google account+ keep in a privacy. Anyway, in earlier post I have posted How to remove friends from Google+, and this post will show you how to block friends from your Google+ account instead of be friend with them.
How to block someone/friends from Google Plus (Google+)
Step 1. Login to your Google Plus account.
Step 2. Click on "Circles" Icon.
Step 3. Then it'll displays the following page contains all of your friends and your circles. Anyway, on this page you also can invite your friends, and create a new circle.
Step 4. To block your friends, you can pick up anyone by clicking on them directly from that page then you click "More Action" tab on the right-upper, then you click "Block"
Like the instruction above, you also can choose one of circle contains friends you wanna block, then after the circle's box displayed, click anyone you wanna block, then click "More Action" tab, then to finish you click "Block".