Iranian officials were caught by surprise over Hamas' attack on southern Israel from Gaza on Saturday, according to US intelligence officials.
US officials who investigated the issue told the New York Times that Iranian officials who expressed surprise were those who often had knowledge of the Islamic Revolutionary Guards Corps (IRGC) Quds Force operations in the region.
The Quds Force is the foreign arm of the IRGC and has been instrumental in supporting Iranian allies in the region including Hamas, Hezbollah, and the Syrian regime.
As well as the US, officials from Israel and other unnamed Middle Eastern countries also reiterated that they had no evidence of Iranian involvement in the attack.
US officials have said that although they have not found evidence of meetings between the Quds Force and Hamas that prepared for the attack, new evidence could always arise.
The officials' statement came after the Wall Street Journal claimed Iran had helped Hamas plan its attack, citing senior members of Hamas and Hezbollah.
The report stated that members of the IRGC had held meetings with Hamas in Lebanon's capital Beirut, alongside Hezbollah members, from August onwards. It also claimed that details of the attack were refined through those meetings.
Iran has denied involvement in organising the Hamas attack, although it has praised Hamas for the operation.
US national security adviser Jake Sullivan blamed Iran for the attack, stating that "We have said since the beginning: Iran is complicit in this attack in a broad sense," citing funding to the organisation, as well as supplying weapons and providing training programs to Hamas fighters.
The current war between Hamas and Israel and siege of Gaza, which has been ongoing since Saturday's Hamas operation, has resulted in the killing of 1,537 Palestinians. At least 1,300 Israelis were killed in the Hamas attack.