The officials said the threats came from groups such as Asaib Ahl al-Haq, Iraqi Hezbollah and Iran's Revolutionary Guards.
The officials stressed that there was "no desire of the (American) administration and no interest in any war with Iran."
The US embassy in Baghdad said earlier on Wednesday that the Foreign Ministry ordered the withdrawal of non-essential staff from both the embassy and the consulate in Erbil.
The US military on Tuesday reiterated its concerns about possible imminent threats from Iran to its troops in Iraq.
US officials said Iran's threat to "our interests and the interests of our allies throughout the region" also called for the US embassy in Beirut to issue a security warning to American nationals.
The officials stressed that Iran would be held accountable "for any action by its agents in the region."