Using 2 different Data Groups to control traffic to a Virtual Server in an iRule

Try this:

when HTTP_REQUEST {
    if { [class match [IP::addr] equals BlacklistedAddresses] } {
        HTTP::respond 403 content "403 - Forbidden"
    } elseif { not ( [class match [IP::client_addr] equals trustedAddresses] ) } {
        HTTP::respond 403 content "403 - Forbidden"
         event HTTP_REQUEST disable
    }
}