Getting error over http and when I am changing url to https then its not working

This is the error I am getting.
I am embedding the URL in the iframe.

Mixed Content: The page at 'https://admin.paypenny.io/pages/dashboard' was loaded over HTTPS, but requested an insecure frame 'http://paypenny-metabase-lb-1221215848.ca-central-1.elb.amazonaws.com/embed/dashboard/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyZXN

and when I tried to change the site_url, it was not present in the general tab.

it's possible because your metabase instance is running on http ... the error is pretty clear content was loaded over HTTPS, but requested an insecure frame 'http