World Bulletin / News Desk

US President Donald Trump's national security adviser said on Wednesday that the United States is not seeking to oust Iran's leadership but wants "massive change" in its behaviour.

The hawkish former UN ambassador who joined Trump's administration in April spoke at a press conference in Jerusalem at the end of a three-day visit that focused largely on Iran, Israel's main enemy.

US and Israeli policy toward Iran has been closely aligned under Trump.

"Regime change in Iran is not American policy, but what we want is massive change in the regime's behaviour," said Bolton, who before taking office advocated regime change in Iran.

Bolton said he believed Trump's decision in May to withdraw from the nuclear deal between Iran and world powers, followed by the reimposition of sanctions, was having a stronger effect than expected on pressuring Tehran.

Echoing Israel's position, he said the nuclear deal had allowed Tehran to finance militant activity in the region due to the lifting of sanctions.

Bolton said that "by bringing the hammer down again of reimposing American sanctions, we've seen a profound negative effect on Iran -- I think actually more serious than we would have predicted."

European countries have sought to save the nuclear deal, saying it is working as intended by keeping Iran from obtaining nuclear weapons for now.

Israeli Prime Minister Benjamin Netanyahu and Bolton have called on European countries to do more to pressure Iran.