Iran's top leader hinted Saturday that he disapproved of the phone call between Presidents Hassan Rouhani and Barack Obama during the Iranian leader's trip to New York last month, but he reiterated his crucial support for the president's policy of outreach to the West.

The comments by Ayatollah Ali Khamenei reflect the difficulties facing Iran's leadership to pursue groundbreaking outreach to Washington without risking a major backlash from hard-line groups uneasy about the pace of the contacts.

In separate remarks, Iran's Foreign Minister Mohammad Javad Zarif said the exchanges with Washington already have paid dividends by opening opportunities to negotiate a "win-win" nuclear deal that would allow Tehran to maintain its uranium enrichment but provide greater assurances the program remain peaceful.

But Iran has not yet given specifics on what it would offer in exchange for possible lifting of Western sanctions when nuclear talks with world powers resume later this month in Geneva.

'Blackmail the world'

Zarif also disputed Obama's claim in an Associated Press interview that Iran was more than year from reaching the capacity to build a nuclear weapon. Zarif repeated Iran's claims that it does not seek nuclear arms, and urged the U.S. and its allies not to allow Israeli Prime Minister Benjamin Netanyahu to "blackmail the world" and block potential progress in nuclear talks. Netanyahu has said Iran could reach the ability to make a nuclear warhead on an even shorter timeframe than suggested by Obama.

"We can't let him determine the agenda of the talks ... Iran won't develop a weapon," Zarif said on a popular talk show on Iranian state TV. "Not six months. Not six years and not 60 years because it doesn't seek one. Netanyahu has been seeking to deceive the world by his lies."

The diplomatic outreach to Washington has critical backing from Khamenei, who decides all major policies. But Rouhani must also be careful not to anger hard-line forces, including the powerful Revolutionary Guard, that worry the new president went too far by accepting a phone call from Obama. The 15-minute conversation was the highest-level direct connect between the two countries since the 1979 Islamic Revolution.

Khamenei, whose speech was broadcast on state TV, also said the U.S. was "untrustworthy." He previously has said he's not opposed to direct talks with the U.S. to resolve Iran's nuclear standoff with the West but is not optimistic.

"We support the government's diplomatic moves including the New York trip because we have faith (in them)," Khamenei told commanders and graduating military cadets in Tehran. "But some of what happened in the New York trip was not appropriate," a thinly veiled reference to the phone call.

Iran is at loggerheads with the U.S. over its disputed nuclear program, which the West says aims at developing weapons technology. Iran says its program is for peaceful purposes and geared toward generating electricity and producing radioisotopes to treat cancer patients.

"We are skeptical of Americans and have no trust in them at all. The American government is untrustworthy, arrogant, illogical and a promise-breaker. It's a government captured by the international Zionism network," Khamenei said.

Negotiating powers

Rouhani said before and after his trip to New York that he had "full powers" to negotiate a deal with the West, an indication that he had received a mandate from the supreme leader, who has final say on all matters of state. His outreach has also received broad support from Iranian legislators and it appears popular, but some including the Guard seem rattled by the pace of developments.

Prominent conservative analyst, Mahdi Mohammadi, said Khamenei's remarks could give Rouhani more room to deal with the West by showing the Iranian president has the power to deal with the U.S. but not an open-ended mandate.

"These remarks increase the government's bargaining powers at talks with the U.S.," he said. "He (Khamenei) has authorized the government to move forward but it's not a blank check," he said in a commentary posted on the tasnimnews.com website.

The Guard's chief commander, Gen. Mohammad Ali Jafari, praised Rouhani recently but called the phone call a "tactical mistake" and said he should have avoided it.

"The respected president, who adopted a powerful and appropriate position in the trip ... would have been better off avoiding the telephone conversation with Obama - in the same way he didn't give time for a meeting with Obama - and left such measures until after practical, verifiable steps by the U.S. government and a test of their good will," he said in an interview earlier this week.

The Guard is one of the few institutions capable of acting as a spoiler if it sees Rouhani going too far and too fast.

Khamenei's remarks may have been prompted by recent statements from Washington that Tehran feels run counter to the spirit of reconciliation.

For example, Obama said Monday, as he met with Netanyahu that the U.S. was not taking a military option against Iran's nuclear program off the table.