Trump: US will no longer uphold Iran ceasefire agreement or hold talks with Tehran

US President Donald Trump has said the United States will no longer uphold the ceasefire agreement with Iran and will not continue negotiations with Tehran.

Speaking during the NATO summit in Ankara, Trump said his decision followed an alleged attempt by the Iranian authorities to kill him.

"We will not allow the crazy Iranians to obtain nuclear weapons. Iran tried to eliminate me and killed thousands of its own citizens. I do not think they understand what they are doing. We have wasted too much time on them, and we will have to do what is necessary," Trump said.

Trump has repeatedly described Iranians as "crazy" and "evil" amid recent developments and said he hated them.

"They are losers, otherwise they would have reached an agreement with us long ago. We have already destroyed their first leadership and then the second. They are evil and sick people. They must be eradicated at the root, like a malignant tumour," Trump said.

He said the ceasefire agreement with Iran was over as far as the United States was concerned and that the memorandum of understanding had been cancelled.

"I am no longer interested in negotiations with Iran," Trump said.