I would look at implementing ACLs to deny access to the IP address of the VLANs. Here is a good white page that covers ACLs on the 6224. [URL] To help control access to the switch one of the first things i would suggest doing is enabling SSH and HTTPS, then disable Telnet and HTTP. 
Hi   i have dell power connect 6224 switch. i have created 3 vlan, Vlan 10,20 and 30. given different Network ip to all vlan .... The problem it can access via telnet or Http from both 3 vlan's IP..  I want it should access from only one IP not from all....... what additional configuration should i do on switch???
Management VLan in Dell Powerconnect 6224