Iran's supreme leader has warned that any “inappropriate” action by the United States in connection with Iran's alleged plot to kill the Saudi Arabian ambassador in the U.S. will bring a “decisive response”.

Ayatollah Ali Khamenei said Sunday that Iran will respond to political or security-related actions by the United States. He also said the U.S. allegations are an attempt to divert attention from its financial problems and protests at home.

Earlier Sunday, Iranian President Mahmoud Ahmadinejad denied the allegations, saying Iranians are civilized and do not need to resort to assassination.

The highest-ranking U.S. Senator on intelligence matters, Diane Feinstein, told Fox News Sunday that U.S. authorities have collected ample evidence showing the involvement of Iran's elite Quds force in the plot.

She added there is “no question” that the Quds force is responsible for plotting several violent terrorist operations.

Last Tuesday, the U.S. Justice Department announced it had broken up an alleged Iranian plot to assassinate Saudi Ambassador to the U.S., Adel al-Jubeir. Officials said the U.S. had filed charges against two Iranians for involvement in the plot. Officials said one suspect was part of Iran's elite Quds Force.

On Friday, U.S. State Department spokeswoman Victoria Nuland said Washington had a direct meeting with Iranian officials over the alleged plot. She told reporters the meeting was to make it “absolutely clear” that the U.S. considers the alleged plot “unacceptable” and a violation of U.S. and international law.