'enforce_for_root' option is not working as expected on Red Hat Enterprise Linux 7

Issue

• Is there a way to enforce the password policy/complexity on root user in RHEL7?
• enforce_for_root option isn't recognized/identified in RHEL7.
• enforce_for_root option isn't working as expected in RHEL7, getting the following error in /var/log/secure:

Nov  9 00:37:05 rhel7 passwd: pam_pwquality(passwd:chauthtok): Reading pwquality configuration file failed: Unknown setting - mindiff
Nov  9 00:37:05 rhel7 passwd: pam_pwquality(passwd:chauthtok): pam_parse: unknown or broken option; enforce-for-root
Nov  9 00:37:05 rhel7 passwd: pam_pwquality(passwd:chauthtok): pam_parse: unknown or broken option; remember=12
Nov  9 00:37:05 rhel7 passwd: pam_pwquality(passwd:chauthtok): Reading pwquality configuration file failed: Unknown setting - mindiff
Nov  9 00:37:05 rhel7 passwd: pam_pwquality(passwd:chauthtok): pam_parse: unknown or broken option; enforce-for-root

• Unable to perform su - getting an error:

$ su - user
su: Permission denied