The problem with retaliation against their oil facilities is it further opens that door of escalation which will increase oil prices and go against the sanctions imposed on Iran. It also crosses the line of a surrogate war and puts Iran in direct conflict with another nation which is something Iran has strived to prevent. So if the attack did originate in Iran this is a huge huge move by them. They may now feel compelled to take a lot more risk because their back is against the wall due to the actions taken by Trump. Lets hope this is all leading to negotiations.