State television added that the missile was Iran's most powerful ballistic missile yet.
"As long as some speak in the language of threats, the strengthening of the country's defense capabilities will continue and Iran will not seek permission from any country for producing various kinds of missile", he said Saturday.
"We will strengthen not only our missiles but also our air, land and sea forces..."
The Khorramshahr missile "has a range of 2,000 kilometers [1,243 miles] with ability to carry multiple independently targetable reentry vehicle (MIRV) within a range of 1,800 kilometers", according to the Tasnim news agency, which is seen as having close ties to Iran's Revolutionary Guards.
The country had previously been known to have a missile of similar range, the Shahab-3, which was based on a North Korean missile.
Other signatories of the deal, namely Britain, France, Germany, Russia and China, do not support the United States stance and believe that Iran has fully complied with its nuclear commitments.
Trump has criticized the nuclear deal and said it must be strengthened, or the USA could walk away. Rouhani said in a speech that Iran would not halt its missile programme but continue to boost military capabilities, despite USA demands. "Iran vows to destroy my country, " he said.
With such a range, the missile would be easily capable of reaching Israel and Saudi Arabia. "Every country in the world is supporting the nuclear deal we signed except the United States and the Zionist regime".
"We will promote our defensive and military power as much as we deem necessary", Rouhani said.
Washington has also taken aim at what it says is Tehran's failure to meet expectations that it would play a more stabilising role in the Middle East. Trump called the deal an "embarrassment" during his first speech at the United Nations on Tuesday. It permits Iran to use nuclear power for civil purposes, but not to build nuclear weapons.
President Donald Trump has threatened to bin the agreement over the issue, saying that Iran's missile program could give it the technical knowhow for a delivery system for a nuclear warhead when a sunset clause in the deal expires in 2025.
But Rouhani ruled out any change of policy in the region. "We will defend the downtrodden people of Yemen, Syria, and Palestine whether you like it or not", Rouhani added.