Iran has assured Washington that retaliation against Israel will not lead to further escalation, while saying it will not act hastily.

Iran’s message to Washington was delivered by Iranian Foreign Minister Hossein Amirabdollahian during a visit on Sunday to the Gulf Arab state of Oman, which often acts as an intermediary between Tehran and Washington, the sources said.

A White House spokesman declined to comment on the specific development, but said the United States had notified Iran that it was not involved in the embassy attack.

Iran’s foreign ministry has also not commented on the news, Reuters reports, as has the Omani government.

A US intelligence source was not aware of the message sent through Oman, but said Iran was “very clear” that its response to the attack on its embassy in Damascus would be “controlled” and planned to carried out “through the supported groups from Tehran”.

The diplomatic message marks a cautious approach by Iran as it weighs how to respond to the April 1 attack in a way that deters Israel from further such actions but avoids a military escalation that could upset the United States.

Iran’s Supreme Leader Ayatollah Ali Khamenei said on Wednesday that Israel “must be punished and will be punished”, saying the attack on the embassy in Damascus was tantamount to an attack on Iranian soil. Israel has not confirmed it was behind the attack, which the Pentagon has said.