Hello,
It depends on how you are sending traffic to the IDSM.
You can use an ACL and deny it there:
ip access-list extended IPS
deny ip any host x.x.x.x
permit ip any any
vlan access-map 10
match ip address IPS
action forward capture
vlan filter 10 vlan-list 800
intrusion-detection module 8 data-port 1 capture allowed-vlan 800
intrusion-detection module 8 data-port 1 capture
Regards,
Felipe.