Minor thing: (Optional)
  Try restarting your Apache after updating the rewrite engine status in vhosts as Rewrite ON.
One critical thing to notice:
  In Apache vhosts file, check whether you have this script line
  AllowOverride None
  If yes, please remove/comment this line. 
My vhosts file script: (Before)
<VirtualHost *:80>
    DocumentRoot "/path/to/workspace"
    ServerName ciproject
    ErrorLog "/path/to/workspace/error.log"
    CustomLog "/path/to/workspace/access.log" common
    Directory   "/path/to/workspace">
        Options Indexes FollowSymLinks
        AllowOverride None
        Order allow,deny
        Allow from all
    </Directory> 
</VirtualHost>
My vhosts file script: (After)
<VirtualHost *:80>
    DocumentRoot "/path/to/workspace"
    ServerName ciproject
    ErrorLog "/path/to/workspace/error.log"
    CustomLog "/path/to/workspace/access.log" common
    Directory   "/path/to/workspace">
        Options Indexes FollowSymLinks
        #AllowOverride None
        Order allow,deny
        Allow from all
    </Directory> 
</VirtualHost>
I faced the same problem, struggled for around 1 day, all were fine. Later, by trial and error method, found this thing. After removing this, my job was accomplished.
The  URL now does not look up for index.php :)