It was not known if any of the hackers managed to gain access to the targeted networks with the emails, which typically mimic legitimate emails but contain malicious software.
CrowdStrike shared images of the spear-phishing emails with The AP.
"We are going to deny them the resources they need to do that, thereby keeping American interests and American people safe all around the world", Pompeo said before leaving to travel for talks on Iran with USA allies Saudi Arabia and the United Arab Emirates.
The Department of Homeland Security said in a statement released Saturday that its agency tasked with infrastructure security has been aware of a recent rise in malicious cyber activities directed at USA government agencies by Iranian regime actors and proxies.
"We will continue to work with our intelligence community and cybersecurity partners to monitor Iranian cyber activity, share information, and take steps to keep America and our allies safe", Mr Krebs said.
The president said he called off the air strikes after being told 150 Iranians would be killed.
US President Donald Trump approved a cyberattack offensive to disable Iranian computers that are used to control rockets and launch missiles, the Washington Post reported on Saturday.
Iran's Foreign Ministry spokesman Abbas Mousavi said the country would welcome a defusion of tensions in the region.
Trump signs executive order to address sticker shock health care costs
Trump has been accused of equivocating on the threat posed by white supremacist individuals and groups during his presidency. The idea behind Trump's order is to give patients practical information they can use to save money.
Woman who accused him of sexual assault not his type
She said he pushed her against a wall, pulled down her tights and assaulted her in an episode that lasted under three minutes. In response to Mr Trump's latest denial and "not my type" comment, Ms Carroll told CNN: "I love that I'm not his type".
Abraham: Chelsea transfer ban provides 'a great chance' to finally breakthrough
There has been speculation that Chelsea might refuse to sell him because of the prospect of a transfer ban hanging over the club. The England U20 global returned for his long term loan from Aston Villa after help them return to Premier League action.
Andrew Murrison, Britain's minister for the Middle East and North Africa, said on Sunday that he had "open, frank and constructive" talks with Iranian government representatives in Tehran.
That was shortly after the aircraft entered Iran's territorial waters off the coast of Asaluyeh city in Bushehr province.
The U.S. has had a contentious cyber history with Iran.
"It will have an effect because it will annoy the Iranians and make negotiations hard to pull off if the supreme leader is sanctioned", said Brian O'Toole, a senior fellow at the Atlantic Council who previously worked in the U.S. Treasury Department's sanctions unit.
The Stuxnet virus, discovered in 2010, is believed to have been engineered by Israel and the U.S. to damage nuclear facilities in Iran.
Iran shot down a US Global Hawk drone on Thursday, saying it had violated its airspace near the strategic Strait of Hormuz - a claim the United States denies. Iranian hackers in 2012 launched an attack against state-owned oil company Saudi Aramco, releasing a virus that erased data on 30,000 computers and left an image of a burning American flag on screens.
"Neither Iran nor any other hostile actor should mistake US prudence and discretion for weakness". The White House did not respond to a request for comment.
Iranian Information and Communications Technology (ICT) minister, Mohammad Javad Azari Jahromi said on Sunday that USA cyber attacks against Iranian targets have not been successful.
Trump told reporters Monday that, "A lot of restraint has been shown by us, a lot of restraint - and that doesn't mean we are going to show it in the future, but I thought that we want to give this a chance", he said.