Washington DC - President Donald Trump on Thursday insisted he should have a role in picking Iran’s next supreme leader after the killing of Ayatollah Ali Khamenei, whose son he said he found "unacceptable."

"Khamenei's son is a lightweight. I have to be involved in the appointment, like with Delcy," Trump told Axios in an interview, drawing a comparison to Venezuela, where interim president Delcy Rodriguez has cooperated with him under threat of violence after the US overthrew Nicolas Maduro.

Trump said the US would likely return to war within five years without a favorable leader in Iran.

"Khamenei's son is unacceptable to me. We want someone that will bring harmony and peace to Iran," he insisted, according to Axios.

It's unclear in what way Trump would be able to take a role in the Islamic republic's selection of a new supreme leader, a decision made by an assembly of senior Shiite Muslim clerics mostly staunchly opposed to the US.

The late Iranian shah's son, Reza Pahlavi, has proposed that he return as a transitional figure before Iran drafts a new constitution as a secular democracy, but he is a widely unpopular figure who has been living in exile for decades.

Ali Khamenei was killed Saturday in an Israeli strike as Israel and the US launched an unprovoked war of aggression, plunging the entire Middle East into chaos and turmoil.

His son, Mojtaba Khamenei, is considered one of the contenders to replace him.