The demonstration is a display of the Iranian lawmakers' anger about Trump's decision.
Saudi Foreign Minister Adel al-Jubeir said that the country would do "everything we can" to build a nuclear bomb.
Reacting to Trump's decision, Iranian lawmakers lit a paper US flag on fire in parliament on May 9, shouting, "Death to America!"
Italy has long-established political and economic ties with Iran, and is its main trading partner within the EU.
Sen. Tom Udall, D-New Mexico, questioned whether Trump has authority under existing laws and the 2001 Authorization for the Use of Military Force (AUMF) to order a "unilateral attack" on Iran.
In either case, Trump made an bad decision.
Trump also won some support in the Arab world for his withdrawal from the deal.
It is clearly shaping up as a discussion that will expose a major cleavage between the US and its G7 partners.
And while the United States itself is not a major customer, foreign companies and other countries that continue to deal with Iran after the wind-down periods will face United States sanctions if they fail to reduce or end their trade.
Iran needs to be confronted not just for its nuclear program, Mattis said, but for its development of ballistic missiles, support for terrorism, launching of cyberattacks and threats to worldwide commerce. "We are unified in our understanding of the threat and in our conviction that Iran must never acquire a nuclear weapon" he said. It was never created to make Iran ideal, even though there was hope the sanctions relief may have eventually convinced the regime to become a more responsible partner to the rest of the world. European Union officials have suggested they'll do what they can to salvage the agreement.
President Hassan Rouhani visits the Bushehr nuclear power plant just outside the port city of Bushehr, Iran, Jan. 13, 2015, in this photo released by the Iranian Presidency Office. He said Iran would decide in "a few weeks" whether to ramp up enrichment.
France said the Iranian nuclear accord was "not dead" despite the US withdrawal. "Everything depends on our national interests".
"After engaging with the US Administration in a thorough manner over the past months, we call on the US to do everything possible to preserve the gains for nuclear non-proliferation brought about by the JCPoA [Iran deal], by allowing for a continued enforcement of its main elements", the statement read. "This was an issue in the past", said one young woman in Teheran.
Larijani also urged the country's nuclear agency to prepare for "resumption of all aspects of nuclear activities".