Blogger Blogspot - How to fix Http to Https redirect SEO violation

Question

In SEO analysis report of my blog, I found this violation message more than thousand times.

The link to "url1" has resulted in HTTP redirection to "url2".
Search engines can only pass page rankings and other relevant data through a single redirection hop. Using unnecessary redirects can have a negative impact on page ranking.

I searched on net and I am feeling like to set either custom robot.txt file to disable crawling of http pages or may be I have to set 301 permanent redirect. Either way can anybody suggest how to do this in blogger/blogspot.