If I understand the new rules correctly, the important thing is not whether you currently hold an Iranian passport or not, but whether you’re a citizen of Iran. Did you successfully renounce your Iranian citizenship when you acquired Danish citizenship? If not, then you’re hit by the new rules and need to get a visa for yourself for the trip.
US authorities have stated that they will revoke the ESTAs for travelers they know are covered by the new rules, but even if they don’t currently know you might still get into trouble if they find out later (say, when you present yourself at the airport).
If your only current nationality is Danish, and you haven’t been to Iran (or one of the other targeted states) later than 2010, then you should be good to go.
Credit:stackoverflow.com‘