Secretary of State Hillary Rodham Clinton called the alleged Iranian plot a "dangerous escalation" in Iran's support for terrorism, saying there must be international response.
Prosecutors on Tuesday accused Iran of plotting to hire a Mexican drug cartel to kill the Saudi envoy with a bomb attack in Washington. The plot included the bombing Saudi and Israeli embassies in Washington, D.C.
The Iranian government denies any knowledge of the plot, calling it a fabrication being made up by U.S. officials trying to divert attention from domestic problems.
Manssor Arbabsiar, 56, and Gholam Shakuri, a member of Iran's special foreign actions unit, have been charged. Arbabsiar is in custody, but the other suspect remains at large.
The Obama administration may lobby for the imposition of new international sanctions as well as for individual nations to expand their own penalties against Iran.
The State Department sent a cable to all American embassies and consulates around the world telling them to put the Iran case before their host governments.
President Barack Obama called it "a flagrant violation of U.S. and international law," and Vice President Joe Biden said on "Good Morning America," "This is really over the top."
U.S. Ambassador to the United Nations Susan Rice will individually brief members of the U.N. Security Council on the foiled plot on Wednesday, the officials said.
The Associated Press contributed to this report.