It's been said already, countless times: Iran was attacked. It's supreme leader (and highest religious authority) killed, its military and civilian officials murdered during Ramadan. Thousands of ordinary Iranian dead, civil infrastructure destroyed, school children massacred.
It is not a peer competitor to the United States, and is therefore using oil as a weapon to ensure the rest of the world have an interest in ending the war (and on its terms). If anything, it has showed incredible leniency by letting any oil out at all.
This isn't rocket science.