Based off the card you want to use this is the ruling on
Rings of Brighthearth: 4/15/2013 A mana ability is an ability that (1) isn’t a loyalty ability, (2) doesn’t target, and (3) could put mana into a player’s mana pool when it resolves.
So the effects of your creatures making mana in the form of tapping is an "Activated ability" but it's considered a MANA ABILITY because of what it does. I hope this helps a little.