hooper-
some more info would be nice.
where were the refs from? was this an official school game? where these high school refs workign a middle school game?
what did you mean when you said you didnt blame the refs for favoring one team over the other. I dont mean to sound defensive

but the suggestion that I as a ref would "favor" one team over the other is so far from my brain that I cant even imagine it.
what "exactly" did you say to the refs? and what was your demeanor and attitude when you said what you said. sometimes i know to ingore a coach just because of how he is talking to me. if he is being a spaz i tune him out, after i rule out the "T". communication isnt just what you said, it is four things: message, messenger, medium, and audience.
lets talk message.
i have to say that "call it tighter for safety" isnt a very clear statement of your complaint. That was probably a bad way to go at the issue. To me that says "coach is just complaining." Obviously, I am going to call a game to make sure it is safe. I dont think any ref is out there disregarding the safety of the kids. So that statement doesnt really say anything to a ref, in my opinion.
now messenger.
how were you acting? what had happened earlier? had you been doing a lot of complaining already? if so, maybe you got tuned out.
medium isnt that relevant.
now audience. the refs themselves. but i've already asked about that above.
one thing, if you had actual observable physical injuries that you claim, call a time out, call the refs over (at this level they will come talk to you i would hope) and SHOW them.
now it is time to be honest: how were your kids playing? just as rough?
how would you have expected the game to be called? do you think calling it differently would have affected the play by the players (particularly at this level)?