How do I prevent my site from redirecting to wp-signup.php

Hello,

When we type "waarba.com" (without the www) into the address bar, our site is redirected to "http://www.waarba.com/wp-signup.php?new=waarba.com". We would like to prevent this redirect. We would like all of our visitors to be directed to our splash page located at http://www.waarba.com.

Can we adjust our settings to prevent the signup page from initiating?

Initially, we were directed to add two lines of code into the .htaccess file, but these lines of code prevented our wildcard subdomains from initiating.

Here is the code we had to remove from .htaccess:
RewriteCond %{HTTP_HOST} !^www.waarba.com [NC]
RewriteRule ^(.*)$ http://www.waarba.com/$1 [R=301,L]

We give thanks in advance!