There is nothing wrong with this. That is just HTML code of the button. If you have buttons on a page, it can be indexed (if that page is indexed). There is no harm in that. Trying to massage or play around with the indexing is not wise. Search engines are super smart and they figure out what is really true content and not.
If you don’t want certain pages to be indexed, then just edit the page or post and use the SEO plugin to specify the page to have no-indexing.
Generally, it is not wise for our plugin to mess with indexing since that is the job of a SEO plugin. You should have a SEO plugin that can allow you to customize the SEO properties of a page (including description).