TEHRAN, May 6 (Xinhua) -- If the United States pulls out of the nuclear deal, it will be a "historical regret" for them, 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" heedless of the threats, he said.

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

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 President Donald Trump decertify the nuclear deal.

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