"We have never been optimistic about the US officials, and the measures and steps that they have taken are in line with their own interests," Velayati told FNA in the Northeastern city of Mashhad on Thursday, referring to the US recent agreement with Iran over the latter's nuclear program.

He said that the Americans have left a bad record of enmity towards Iran after the Islamic Revolution and Kerry's remarks were not unexpected.

Kerry stated in an interview with the MSNBC that “if we do the right job of inspecting, and Israel, and the [persian] gulf states, and we and our friends, France, Germany, Britain, China, Russia all are doing the right level of intelligence gathering, believe me, we will know what Iran is doing”.

In relevant remarks today, Supreme Leader of the Islamic Revolution Ayatollah Seyed Ali Khamenei blasted the US statesmen for their contradictory remarks after the nuclear agreement with Tehran, and called on Iranian officials show more sensitivity and give proper response to their comments.

"In the nuclear talks with are negotiating with the 5+1, but the US administration is, in fact, the main party; but the US officials speak very badly and a decision needs to be taken about the manner they speak," Ayatollah Khamenei said in a meeting with the head and members of Iran's Assembly of Experts in Tehran.

"Don’t say that the Americans are uttering these words to convince their internal rivals; of course, I believe that the internal disputes in the US are real and they have differences and the reason for such a difference is clear to us but what is officially said needs a response and if no response is given to them, the other side's remarks will be entrenched," he added.

Ayatollah Khamenei also referred to the US officials' remarks on the suspension of sanctions, and said Tehran has always underlined the necessity for the termination and not suspension of embargoes.

"If the sanctions are not due to be removed, then there will be no deal either. Hence, there needs to be a decision to be taken in this regard," he added.

He said Iran has made some concessions during the negotiations with the world powers in order to see a removal of the sanctions in return, otherwise we wouldn't have attended the negotiations and Iran could have increased its 19,000 centrifuges to 60,000 centrifuges, continue 20% uranium enrichment and accelerate its research and development activities.

"If the sanctions are due to be suspended, our actions should also be arranged in the form of suspension and not essential measures on the ground," Ayatollah Khamenei said.

"Of course, the other side says that removal of certain sanctions is not within the US administration's authority; in response we say that those sanctions that fall under the US administration and the European governments' authority should be terminated," he added.

Ayatollah Khamenei also blasted the US officials' remarks that the Joint Comprehensive Plan of Action (JCPOA) has created some opportunities for the Americans both inside and outside Iran and in the region, and said, "The Iranian officials shouldn’t allow the US to make use of any opportunity inside the country and they should also try in order not to allow the Americans to find any such opportunity outside Iran because the closer they come to such opportunities, the worse the nations' sufferings, humiliation and backwardness will grow."

He reiterated the complete ban on any negotiation between the Iranian officials and the Americans on other issues, and said there won't be any other talks with the White House, except for the the nuclear issue, because "the US positions are fully against the stances of the Islamic Republic."

Ayatollah Khamenei said the US cannot treat Iran as it does with regard to some other underdeveloped countries, and stressed that Iran is a powerful nation and has already proved its capabilities in action.

He referred to the US officials' remarks that they expect Iran to pick up a different course of action, and said they mean ignoring the Islamic values, non-commitment to the Islamic laws and Iran's confirmation of the US policies in the region which include full annihilation of the resistance forces and full hegemony over Syria and Iraq, but they should know that "such a thing will never happen".

Elaborating on the process of the JCPOA's approval in Iran after the nuclear agreement was reached with the world powers in Vienna on July 14, Ayatollah Khamenei underlined that the JCPOA should be precisely scrutinized by experts, and stressed that the parliament should certainly play a role in this regard.

Yet, he said he reserves judgment on the agreement and would not advise "the parliament on how to study the JCPOA or on approving or disapproving it. These are the people's representatives who should decide about it."

Iran and the world powers reached a final agreement in Vienna on July 14 to end a 13-year-old nuclear standoff.

A week later, the UNSC unanimously endorsed a draft resolution turning into international law the JCPOA reached between Iran and the 5+1 group of countries (the US, Russia, China, Britain and France plus Germany) over the Islamic Republic’s nuclear program.

Now the US Congress and the Iranian parliament have less than 50 days to review the deal to approve or reject its practice; FNA reported.