With regard to U.S. sanctions on gasoline on Iran:

Obama said the new sanctions were the toughest ever passed by the U.S. Congress and would make it harder for Iran to buy refined petroleum as well as goods and services to modernize its oil and natural gas sector, the mainstay of its economy.
Obama says new U.S. sanctions on Iran toughest ever, Reuters, July2 2010

With regard to Iran’s sanctions on gasoline exports on U.S.-Afghanistan:

QUESTION: Some kind of economic tension is brewing up between Afghanistan and Iran. Iran has blocked the supply of gas to Afghanistan, which has led to increasing gas prices and shortages of gas in Afghanistan. What do you have to say about that – on that?

MR. CROWLEY: I mean, we are watching closely that development. Energy is a critical resource to any country and any economy, and it should be available at whatever the appropriate market price is.
Daily Press Briefing, Department of State, January 12 2011

h/t Ali Gharib

Question: What will the U.S. say when Iran is successful with its current engineering of a democratic(!) regime change in Lebanon?