Can't remove it from pages without shortcode option

I want the twitter icon to appear on posts only — not on pages. I don’t want to use the shortcode method, because then I have to add the shortcode to every post. I want it to automatically appear on every post, but not on pages. Currently, it is appearing on pages too. How can I remove it from pages, but leave it on posts? Here is an example of a page with the Twitter button that I want to remove:

http://djmix.top10select.com/sitemap/

http://wordpress.org/extend/plugins/twitter-plugin/