Go into the search service associated with the application (Application Management > Manage service applications) and create a new Server Name mapping. Put in something like this:
Address in index:
Address in search results:
This is usually used with an alternate access mapping to control the address your users see vs. what's actually set up in SharePoint, but will work solely on search results without the AAM. Keep in mind that by itself, this will only make users see the 2nd address in the results - when they click on the link they will still go to the 1st address.