<var:client:isAdmin> - If the client is admin (bool)
<var:client:isSuperAdmin> - If the client is super admin (bool)
Got this from the manual. I think this might be what you're looking for.
Basically, you could just do
on(trigger) -> ifvalue -> <var:client:isAdmin> == 1 [1 2]
onvariabletrue -> something
onvariablefalse -> client -> centerprint [You are not an admin!]
Hope that helped.