Attempts to distract pitcher from dugout

Question
I was umpiring an ASA fast pitch 12-U girls game during which the offensive team would distract the pitcher, saying things like "Your shoelace is untied." just before a pitch.  They also would shout or whistle just as the ball was about to be released.  I quickly put an end to the unsportmanlike chatter.  My question is, where in the rulebook, if at all, is such chatter prohibited?

Answer
Thanks for the question!

Where I umpire, we've always done the same thing you did.  Nip it in the bud early and often.

While there isn't anything specific in the rule book I personally lump it under Point of Emphasis #49 Sporting Behavior - The values of softball competition are based on sporting behavior and fair play.  Coaches and players are expected and trusted with these values.

The book lists some examples but the rule is not limited to just those examples.  Nothing like blanket protection!

I hope this answers your question!  If not please reply.