^M of CRLF shows up in git, but not vim

To my django web project, I'm adding HTML files from a template. In Vim, these HTML files don't show anything wrong, i.e. no CR characters are visible. But when I do a git diff, they show up. Since they're not visible in Vim, I'm not able to do :%s/^M//g or :%s/\r//g, as both of them show pattern not found error. BUT they're still visible in git diff. I don't want them to be seen in git. git config --global core.autocrlf true doesn't help either