Hello Badr,
The error MUTATE_ACTION_NOT_PERMITTED_FOR_CLIENT indicates that the operation is not permitted through the API. If you're referring to the
TrueView in-search video template ads with template ID: 231 will no longer accept new ads for that template, for display network campaigns. You may refer to
this blog post for more information. If that's not the case, could you please share the API SOAP logs so I can take a look. You may refer to
this guide on how to enable logging for the PHP client library. You can reply back via Reply privately to author option.
Thanks,
Bharani, AdWords API Team