web filter for https request

Hello , 

I run into this issues, 

internet -> fortigate -> fortiauthenticator (with reset password service)

everithing working correctly also fortytoken service , but i would like to restrict the access only for request addressed to https://urlfortigate/portal/selfservice/reset_password

this url open a web page on 443 for reset password service.

I wish to block every others web page that coming from internet to fortiauthenticator.

i though a webfilter that permit only 

urlfortigate/portal/selfservice/reset_password -- simple -- allow

* -- wildcard -- block

but another configuration is put the firewall policy using a certificate inspection.

If i use this config when the internet user can try to reach the fortiauthenticator web page to reset own password obtain that " you are not allowed to access this resource" ... i think is a fortiauthenticator message but i do not understand where this message born ... 

someone has tried to experience this issues ....

thank you