U.S. authorities said on Tuesday they had broken up a plot by two men linked to Iran's security agencies to kill the Saudi envoy, Adel al-Jubeir. One man was arrested last month while the other was believed to be in Iran.
"These claims are vulgar ... It is a childish and amateur game," parliament speaker Ali Larijani told parliament in a speech broadcast live on state radio.
"We believe that our neighbors in the region are very well aware that America is using this story to ruin our relationship with Saudi Arabia."
Foreign Minister Ali Akbar Salehi dismissed the allegations, saying the United States would have to apologize for its words.
"U.S. allegations are mischievous and I assure you they will apologize in the future," Salehi was quoted as saying by Iran's Arabic-language television network Al Alam.
In London, a former chief of Saudi intelligence services said evidence that Iran was behind a plot to kill the Saudi Arabian ambassador to Washington was overwhelming. Read More