TEHRAN, May 6 (Xinhua) -- If the United States pulls out of the nuclear deal, it will be a "historical regret," Iran's President Hassan Rouhani said here on Sunday.

Rouhani dismissed Washington's threats, saying that the Iranians are not afraid of the United States. "This great nation will continue its progress and development" regardless of the threats, he said.

Rouhani said that the Islamic republic is prepared for any decision by the United States regarding the nuclear deal.

"We must know that (the United States) next week decision will not change our lives," he said.

The Iranian government has given necessary instructions to the executive bodies of the country since a couple of months ago, and "the Atomic Energy Organization of Iran has also received orders to deal with the possible U.S. withdrawal from the nuclear deal," he said.

Iran has threatened to resume nuclear enrichment activities in case U.S. President Donald Trump decertifies the nuclear deal.

Trump is expected to decide by May 12 whether to pull out of the nuclear deal, and he has said that he would not extend the waiver suspending the U.S. sanctions on Iran.

In January, Trump extended sanctions relief on Iran under the deal for the last time, threatening to withdraw from it if U.S. congress and his European allies cannot fix the alleged "disastrous flaws."

The whole world, except the United States, Israel and Saudi Arabia, is supporting the nuclear agreement. The Iranian president lashed out at Trump's call on the Europeans to join his plan.

"I overtly announce to the whole world, Europe, America, the West and the East that we will not negotiate with anyone about our country's weapons and defense programs," said Rouhani.

"We will build and store any amount of weapons and missiles the country may need. It is none of anybody's business what decision the Iranian people have made for their defense," he stressed.

Moreover, Iranian Parliament Vice-Speaker Ali Motahhari said Sunday that the U.S. scrap of nuclear deal would be a "double win" for the Islamic republic.

In case Washington leaves the nuclear deal, on the one hand it will lose its international position and, on the other, Iran would no longer be obliged to fulfill its undertakings under the JCPOA, Motahhari was quoted as saying by Tasnim news agency.

On Sunday, Ali Akbar Velayati, senior advisor to Iran's Supreme Leader Ayatollah Ali Khamenei, also said that "if Americans opt to quit the nuclear deal, the Islamic republic is ready to counter their measure in a proportionate manner," Press TV reported.

Iran has an open hand to respond to any decision about the fate of the JCPOA, Velayati said, adding that the Americans can test this issue.

Also, Chief of Staff of the Iranian Armed Forces Major General Mohammad Baqeri said that the country's armed forces are ready to deal with any possible threat posed by enemies of the Islamic republic.

"At the present time, the armed forces are maintaining a high level of readiness to give a response to any threat and act of aggression by enemies of Iran," Baqeri told a gathering of military forces in Iran's southwestern Khuzestan Province on Sunday.

He added that "the world-devouring America, the usurping Zionist regime (of Israel) and regional reactionary regimes have been trying to threaten and deal a blow to the Islamic Revolution of Iran for the past 40 years," he said.

However, "the enemies of Iran" have not been able to deal even a slight blow to the Islamic republic, he said.