How to modify the content security policy (CSP) response header for Safari App Extension?

It is posssible to modify the content security policy (CSP) response header for google chrome extension.
for more details: https://developer.chrome.com/extensions/contentSecurityPolicy
I have created the application for Safari App Extension and want to modify the content security policy (CSP) response header.
How to modify CSP header for Safari App Extension.
I would appreciate if any help.
Thanks in advance