U.S. President Barack Obama has signed an executive order that imposes new sanctions on Iran's energy and petrochemical sectors, to prevent that country from circumventing international penalties for its nuclear program.

Additionally, the U.S. Treasury Department announced sanctions against one Chinese and one Iraqi financial institution accused of doing business with sanctioned Iranian banks.

In a statement by the White House Tuesday, the president said the new measures strengthen efforts to pressure and isolate the Iranian government for “its continued failure to meet its international obligations.”

The White House action comes as the House of Representatives and the Senate prepare to introduce their own sanctions against Iran. Some lawmakers have criticized the president for not being tough enough on Iran.

The United States and several other Western countries have united to impose sanctions on Iran, saying they are concerned that Iran's nuclear program is an effort to develop nuclear weapons. Iran says its programs to enrich uranium are for civilian purposes.