https://economictimes.indiatimes.co...ne-middle-east-crude/articleshow/69933320.cms There is less and less room for Iranian oil on the market and more and more for the American oil. Conspiracy theorists may argue that the whole point of confrontation with Iran was to sell as much American oil as possible. But others (like me for example) would just be happy to see that some action made by the United States that is morally right (sanctions against Iran) also turns out to be profitable for its industry.
Iran also refused to cooperate with Opec, (cut supply to increase prices) financially this was disastrous for Saudi Arabia's oil dependent economy and highly indebted American oil companies with their short oil well lifespan and high development cost. Today America is the biggest oil supplier and I believe Russia just became China's biggest supplier.
Right now Iran is cutting its supply because America is hitting it hard with sanctions. But the problem is that oceans are big and it's not that easy to find those ships that are carrying the Iranian oil. And even if you do find them there is a question of how far you are willing to go to punish them.