Request filter for Dynamic IP Address Restrictions?

Hi guys,

I am developing some kind web apis and I want to minimize the possibilities of Brute-force-cracking of the passwords of my Web Server. Luckily I find Dynamic IP Address Restrictions, but it seems client may have large mount of requests over a small period of time after login. So is there a way to filter request for Dynamic IP Address Restrictions, for example, just login requst have Dynamic IP Address Restrictions?

Thanks,
Pan