Iranian Foreign Ministry spokesperson Esmail Baghaei said during a press conference on Monday that the U.S. bears ultimate responsibility for any escalation between Iran and Israel, following their exchange of direct strikes on Sunday through into Monday.
"In our region, nobody believes that any action by Tel Aviv takes place without coordination with the United States," Baghaei said, as quoted by the official Islamic Republic News Agency.
"The United States' responsibility in the Israeli regime's acts of aggression is clear, and Washington will bear responsibility for the consequences of escalating tensions," he added. "Despite American claims, we know they are currently cooperating with Tel Aviv in both offensive and defensive operations."
Baghaei said that if the "basis of the negotiations," including the ceasefire in Lebanon, is violated by Israel or by the U.S., then the ongoing diplomatic process cannot continue.
"Attacks on our southern regions and the assault on Lebanon are being carried out under direct U.S. responsibility, and they must be held accountable for these crimes," Baghaei said.
Baghaei said Tehran will continue its "defensive measures" as long as it deems it necessary for the country's national security.
"We remain engaged in message exchanges with the United States," Baghaei said, warning that Tehran "cannot separate" Israeli and U.S. conduct.
"So far, our exchanges with the Americans have taken place in an atmosphere of deep mistrust, and the developments of the past 24 hours will only intensify that distrust," he added.
-ABC News' Somayeh Malekian