Iran's nuclear programme was at the centre of discussions on Wednesday between US army chief General Martin Dempsey and Israeli Defence Minister Moshe Yaalon, public radio said.

"The Iranian regime is involved in all of the conflicts in the region," the radio quoted Yaalon as saying during talks in Tel Aviv with Dempsey which were also attended by Israeli armed forces chief of staff General Benny Gantz.

Iran was also the focus of talks Dempsey held on Tuesday with Prime Minister Benjamin Netanyahu.

The radio said US military commander wanted to ensure Israel would not launch a pre-emptive strike against Iran's nuclear programme, which the Jewish state sees as geared towards developing an atomic warhead.

Despite Iran's election of a new president, Netanyahu has kept up anti-regime rhetoric, denouncing Hassan Rowhani as a "wolf in sheep's clothing" who would "smile and build a bomb."

Rowhani said last week Iran was ready to hold "serious" talks with the major powers without delay to allay Western concerns about its nuclear programme.

Dempsey's visit came as Israel and the Palestinians prepared to hold their first round of direct peace talks in nearly three years, against a background of Palestinian anger over fresh settlement expansion plans.

Iran's supreme leader Ayatollah Ali Khamenei on Friday warned the Palestinians against renewed peace talks, saying they would be "detrimental" to their cause.

Negotiations, warned Khamenei, would only "encourage the aggressors to increase their aggression and suppress the rightful resistance of the Palestinians."