Plesk 12.x / Linux :: Subdomains Redirect Www Prefix

We are starting to migrate our servers to Plesk and are building all necessary processes with the plesk xml api.

If I create a subdomain via api

Code:
<subdomain>
<add>
<parent>domain.com</parent>
<name>example</name>
<property>
<name>www_root</name>
<value>httpdocs/web/</value>
</property>
</add>
</subdomain>

The vhost configuration at apache gets this part

Code:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^subdomain.domain.com$ [NC]
RewriteRule ^(.*)$ http://www.subdomain.domain.com$1 [L,R=301]
</IfModule>

So every subdomain is redirected to prefix www. But if I create the subdomain via plesk panel, the mod_rewrite isnt created, as i want. I also tried reconfigure-all, but this rewrite part is always active. I have no possibility in plesk 12.0.18 to set the setting for www prefix like at normal sites. So what can i do to prevent it and where can i change it afterwards?