Sonicwall HTTPS filtering

I recently acquired a sonicwall 250 NSA with most licenses but the DPI-SSL (at the time I did not know the impact this license had) and  I came across a problem when filtering content to my users.. well https is not filtered at all... and lots of sites use https. So I tried to create a firewall rule that would deny https to some users but, as it turns out . you cant do this so... does anyone know a workaround or a method to if possible filter https (yes I tried the Enable HTTPS Content Filtering checkmark)  and if not possible to deny traffic to some users at the https service and allow others...

Thanks!