Oil pump
Oil pumpIsrael news photo: Morguefile

The U.S. is lobbying other countries to cut down their imports of Iranian crude in hopes of pressuring Tehran into stopping its nuclear development activities.

U.S. government sources were quoted Thursday by The Wall Street Journal
 as saying American officials are urging countries that import large quantities of oil from Iran to make significant cuts in their purchases.

As part of the effort, the U.S. has levied sanctions against Iran's Central Bank. The European Union is also working on an embargo against imports of Iranian oil as well.

However, a number of countries have already raised questions with the U.S. regarding temporary exemptions from sanctions signed into law by President Barack Obama on Saturday, including South Korea.

China has already cut its imports from Tehran by more than half this month, and has begun to purchase its supplies of crude instead from Russia, Vietnam, West Africa and Iraq, according to the Reuters news agency.