Did we?
Wikipedia says no. (I know, I know. Trusting Wikipedia is risky.)
However, the United States has never admitted responsibility, nor apologized to Iran.[8]
http://en.wikipedia.org/wiki/Iran_Air_Flight_655
At no point did we deny that USS VINCENNES launched the missile ... we expressed ‘regret’ for the loss of life ... we forked over the bucks.
Even wikipedia agrees with that.
The Russians/Soviets, OTOH ...