Israel's international affairs minister on Thursday said there were "small differences" with the United States over the Iranian nuclear issue, a week after direct talks between Tehran and world powers.

"We generally see eye to eye with the Americans on the final objective, which is to prevent Iran from getting a nuclear weapon, but there are sometimes small differences over the way to do that," Yuval Steinitz, who is also intelligence minister, told Israeli public radio.

Steinitz, who is on a visit to the US for discussions on Iran, did not elaborate, but added that sanctions against Tehran must not be relaxed until there is "an agreement guaranteeing 100 percent that Iran will never be able to have a nuclear weapon".

Israel has repeatedly warned against the so-called charm offensive of Iran's new President Hassan Rouhani, which led to direct talks between Tehran and the P5+1 countries -- United States, Britain, France, China and Russia plus Germany -- in Geneva on October 15 and 16. Another round of talks is slated for next month.

The Jewish state, the Islamic republic's arch-foe, has insisted there be no relief for Iran from crippling economic sanctions which it says brought it to the table in the first place.

Israel, the Middle East's sole if undeclared nuclear-armed power, wants Iran to meet four conditions before the sanctions are eased: halting all uranium enrichment; removing all enriched uranium from its territory; closing its underground nuclear facility in Qom; and halting construction of a plutonium reactor.

Western countries, along with Israel, suspect Iran's nuclear activities are aimed at military objectives, a claim Tehran vehemently denies.

Steinitz said Israel does not oppose Iran's right to civilian nuclear energy, but insisted it must not be able to enrich its own uranium, which is required for nuclear fuel but can also be used to develop a warhead.

Israel's President Shimon Peres, meanwhile, linked the Iran nuclear issue to the wider topic of regime change in the Middle East.

"All of us are concerned about the enrichment of uranium but there is a wider picture," he told a conference organised by right-leaning newspaper the Jerusalem Post.

"Dictatorships only seem strong but they are the weakest, an Iranian Spring is possible; don't underestimate the power and ability of the people," Peres said.

Justice Minister Tzipi Livni, speaking at the same event, said that Arab countries could join an "axis" with Israel to counter the Iranian threat, but only if peace talks with Palestinians made headway.

"The fact that the conflict with the Palestinians has not been settled is preventing Arab countries threatened by Iran from overtly collaborating with Israel.

"Progress in negotiations will weaken Iran and allow for an axis comprising Arab countries and Israel against Iran," Livni said.

Ahead of talks in Rome with Israeli Prime Minister Benjamin Netanyahu on Wednesday, US Secretary of State John Kerry said "words are no substitute for actions" on the Iran nuclear issue, adding that it was too early to talk about easing sanctions on the country.

At the same time he hailed the recent signs of openness in Iran following Rouhani's election and said the country should now respect the same rules as other nuclear powers.