The firewalld rule is optional.

defaults/main.yml

@@ -10,3 +10,5 @@ ntp_define_servers_pool: False
 ntp_servers_pool: []
 # - x.y.z.w
 # - w.y.z.x
+
+ntp_enable_default_firewalld_rule: 'enabled'

tasks/main.yml

@@ -34,8 +34,8 @@
     service: name=ntpd state=stopped enabled=no
     when: not ntp_service_enabled | bool
 
-  - name: Manage the ntp firewalld rules in zone {{ firewalld_default_zone }}
-    firewalld: service=ntp zone={{ firewalld_default_zone }} permanent=True state=enabled immediate=True
+  - name: Manage the ntp firewalld rules in the {{ firewalld_default_zone }} zone
+    firewalld: service=ntp zone={{ firewalld_default_zone }} permanent=True state={{ ntp_enable_default_firewalld_rule }} immediate=True
     when: firewalld_enabled | bool
 
   when: ansible_distribution_file_variety == "RedHat"