Kerry said that Saudi Arabia's late king Abdullah and Egypt's ousted president Hosni Mubarak had both told him that the United States should attack Iran, even while they would not take the position publicly.

By pulling out of the accord, President Donald Trump has "made it more likely that there will be conflict in the region because there are people there who would love to have the United States of America bomb Iran," the former senator and presidential candidate told the Council on Foreign Relations as he promotes his memoir, "Every Day

Kerry spearheaded diplomacy that led to the 2015 agreement in which Iran promised Western powers, Russia and China to scale back its nuclear program drastically in return for sanctions relief.

Former secretary of state John Kerry voiced fear Friday of conflict with Iran after the United States pulled out of a denuclearization deal, saying regional leaders had privately pressed him for military strikes.

Israeli Prime Minister Benjamin Netanyahu, an outspoken critic of the Iran deal, had also asked then US president Barack Obama for the green light to bomb Iran, Kerry said.

While UN inspectors found that Iran was complying with the accord, Trump declared the deal to be a disaster for not addressing other US concerns with Iran including threats to Israel, support for Islamist militant moves such as Hezbollah and Tehran's missile program.

But Kerry said the United States was "actually getting them to do things, quietly," including on easing the conflict in war-ravaged Yemen, and believed that President Hassan Rouhani was "trying to move the country in a different direction."

"What Trump has done is now empower the guys in Iran who said don't deal with the United States, they'll burn you," Kerry said.

"He has made it more likely that if there is an implosion in Iran internally through pressure or otherwise, it will not be an unknown Jeffersonian democrat who is going to appear and take over, it will be the IRGC or another Ahmadinejad, and we will be worse off and the people of Iran will be worse off," he said, referring to the hardline Revolutionary Guards and former firebrand president Mahmoud Ahmadinejad.

Trump has lashed out at Kerry for meeting Iranian Foreign Minister Mohammad Javad Zarif since leaving office, accusing him of violating an obscure US law that prohibits private citizens from negotiating on disputes with foreign governments.

Kerry said Trump was seeking to distract from his own scandal related to alleged Russian interference in the 2016 election and said it was normal for former officials to maintain communication with foreign counterparts.