It has been solved here :
Let me explain more :
suppose we want to give ip address from our pool to our office clients dynamically. and we want that nobody outside of our office who come into our office with his laptop and set it’s NIC configuration to get dynamic IP address can get any IP address from our pool. and also if he/she set it’s IP address settings to static ip - some ip in our pool range - again he/she could not access to our network or Internet.
here is the answer:
http://forum.mikrotik.com/t/preventing-any-static-ip-allocation-on-dhcp-router/52165/1
good luck.