Safari keeps redirecting http to https

Whenever I try to open a certain http website, Safari says that the same site with https before is not available.

Safari is actually not wrong, since that site doesn't have any https page, but the point is that Safari keeps redirecting when it's not needed at all!

Please, bear in mind the following.

• I cleared Safari history, cookies and website data
• I previously visited that same site when it had all pages in https
• I noticed that some other browsers that previously visited the site (e.g. a friend's Chrome on Android) does the same
• Beside Safari I run Firefox and Chrome, which previously didn't visit the site: both of them open the site without any similar issue
• Everything above is true both on my Mac and on my iPhone (6 with latest iOS)

Any hint on how to let Safari open up that site, without having to switch to another browser?