US Secretary of State John Kerry slammed Iran on Friday for its barring of would-be candidates for a presidential election next month.

"I cannot think of anyone in the world... who would not be amazed by a process in which an unelected Guardian Council, which is unaccountable to the Iranian people, has disqualified... hundreds of potential candidates according to vague criteria," he said at a news conference in Tel Aviv.

"The council narrowed a list of almost 700 candidates down to... officials of their choice, based solely on who represents the regime's interests, rather than who might represent some different point of view among the Iranian people," Kerry said.

"The lack of transparency makes it highly unlikely that that slate of candidates is either going to represent the broad will of the Iranian people or represent a change," the top US diplomat added.

Ahead of Iran's June 14 election to replace President Mahmoud Ahmadinejad, the conservative-dominated Guardians Council winnowed the candidate field from 686 to eight, all of whom are close to supreme leader Ayatollah Ali Khamenei.

Rejected candidates include Akbar Hashemi Rafsanjani, a moderate who served as president from 1989 to 1997, and Esfandiar Rahim Mashaie, a controversial aide to Ahmadinejad.

Ahmadinejad himself is constitutionally banned from seeking a third consecutive term.

The disqualifications appeared to leave lead nuclear negotiator Saeed Jalili, a figure close to top decision-maker Khamenei, as the frontrunner.

Kerry's criticism echoed US reactions earlier in the week to Iran's disqualification of would-be candidates. He spoke at the end of a visit to meet Israeli and Palestinian leaders in Jerusalem and Ramallah respectively. 

"It appears that Iran's unelected Guardian Council, which is unaccountable to the Iranian people, has disqualified hundreds of potential candidates based on vague criteria," State Department deputy spokesman Patrick Ventrell said on Tuesday.