I can guarantee you that no record of any such arrest exists in paper or electronic form anywhere in a database that can be queried in Pakistan, even if US immigration authorities had a way to get cooperation from Pakistani federal police authorities without involving very high-level diplomatic contacts. Answering truthfully on a question like that will just fuck up your own case.
Is it still being legitimately arrested if you've been detained unlawfully for a shakedown by corrupt police? The same happens in many developing nations. It's actually more like being kidnapped.
Some of the process of using other data sources to verify that what a person has said is truthful/factually accurate only works if you're dealing with people coming from places with non-corrupted legitimate record keeping and bureaucratic processes.