Supreme Leader of the Islamic Revolution of Iran Grand Ayatollah Sayyed Ali Khamenei stressed Saturday that United States cannot be trusted.

Supreme Leader of the Islamic Revolution of Iran Grand Ayatollah Sayyed Ali Khamenei stressed Saturday that United States cannot be trusted, criticizing some aspects of latest visit of Iranian President to UN General Assembly meeting in New York last week.

"We support the diplomatic initiative of the government and attach importance to its activities in this trip," Imam Khamenei told military commanders and graduating cadets.

However he added -- without elaborating -- that "some of what happened in the New York trip was not appropriate," in an implicit reference to the 15-minute telephone conversation between President Sheikh Hasan Rouhani and his US counterpart Barack Obama.

Diplomatic sources revealed that Sheikh Rouhani agreed to talk with Obama after the latter asked for such a call for five consecutive times.

"We are pessimistic towards the Americans and do not put any trust in them. The American government is untrustworthy, supercilious and unreasonable, and breaks its promises," Sayyed Khamenei said, who has the final say on all matters of state including foreign policy.

The Supreme Leader also slammed Washington for its alliance with Iran's number one regional foe, the Zionist entity.

The American administration "is a government that is seized by the international network of Zionism, and has to put up with the usurper (Zionist) regime and show flexibility towards it," Imam Khamenei said.

Zionist Prime Minister Benjamin Netanyahu secured a tougher line from Obama in his public comments after their White House talks last Monday, sparking Iranian accusations of "flip-flop" by the US president.

In his address to the UN General Assembly last Tuesday, Netanyahu then warned that Israel was ready to go it alone in taking military action to prevent any possibility of Iran developing a nuclear weapons capability.

Khamenei said any such action would be met with a "harsh" response.

"We hear the repetitive and disgusting threats of the Iranian nation's enemies. Our response to any mischief will be serious and harsh," he said.