Iran's foreign ministry summoned the Swiss ambassador to Tehran, Livia Leu Agosti, to condemn the Congressional committee session "on the issue of assassinating Iranian officials," the website of Iran's state broadcaster said.
The Swiss embassy handles US diplomatic matters in the absence of diplomatic ties between Iran and the United States.
"Considering the threats made against the Iranian officials in this session, in case of any kind of terrorist action against Iranian officials, the American government will be held responsible," an unnamed foreign ministry official reportedly told Leu Agosti.
Iran was complaining about testimony given to the US Congress's Homeland Security Committee on October 26th by two military analysts invited to speak as expert witnesses.
The first, a US retired four-star general who helped plan the US-led occupation of Iraq, Jack Keane, called for the killing of leaders of Iran's Quds Force in retaliation for their alleged role in a plot to kill the Saudi ambassador to Washington.
"Why don't we kill them? We kill other people who are running terrorist organisations against the United States," he said.
The other witness, Reuel Marc Gerecht, a former CIA officer who is now a senior fellow at the neo-conservative think-tank the Foundation for Defence of Democracies, agreed.
"I dont think that you are going to really intimidate these people, get their attention, unless you shoot somebody," he said, arguing that an attempt should be made to capture or kill the head of the Quds Force, Qassem Suleimani.
Several US congressmen on the committee said they were not excluding any measures against Iran, but they did not explicitly endorse Keane and Gerecht's advice.
The Iranian foreign ministry official who spoke to the Swiss ambassador reportedly said however that the argument for assassinations "contradicts Washington's legal obligations in combatting terrorism."
Iran has fiercely denied any involvement in the alleged assassination plot against the Saudi ambassador and sent a letter to Washington demanding an apology.
It has called the accusations an attempt by the United States to distract attention from domestic economic problems and a failed foreign policy in the Middle East.