You need to be a bit careful.
If you were arrested for the offense (even if no conviction followed) then a visa is definitely required. However, further to that, from the US Embassy website:
“Travelers with minor traffic offenses which did not result in an arrest and/or conviction for the offense may travel visa free, provided they are otherwise qualified.”
My reading of that is that if you were convicted by a court (as opposed to accepting a fixed penalty) the Visa Waiver facility may not be available. Apparently the only way to find out for sure whether or not you need a visa in these circumstances is to apply for a visa !