Rails application to not redirect to HTTPS on specific controller and action

How can my application not redirect to HTTPS on a certain controller and action ? In my case it's the controller transaction and action update_payment. I'm having loop redirect problem on production.

I've tried using the the gem rack-ssl-enforcer and putting the following in the production.rb:

config.middleware.use Rack::SslEnforcer, :except => [%r{update_payment$}], :strict => true

Still, it seems it's not working..