You have just installed the Disqus comment system on your WordPress blog and now you see it appearing all over the show, on both pages and posts alike. I ran into the same issue and for obvious reasons only wanted to show it on single blog posts and would love to share how I fixed this with you.
There are only two simple steps so be sure to do exactly as I explain.
Disqus is added to your posts and page alike through the WorPress ‘comments_template’ filter. In order to override this we will have to disable this filter from being called by the plugin. To do this add the following code to your theme’s functions.php:
This will only disable Disqus, but will still show the default comment system, which we’ll remove in the next step.
The final step will simply be to remove the default comment system from pages as well. To save you some time there is already a plugin that does this: http://wordpress.org/plugins/disable-comments/
After installing and activating this plugin. Go over to the settings and make sure you select by post type option ensure that only blog posts are unchecked ( meaning comments will be hidden for the checked post types).