Under the nuclear deal, known formally as the Joint Comprehensive Plan of Action, Iran agreed to curb its nuclear program in return for sanctions relief.
The United States walked away from the international pact on May 8, 2018, and reimposed several rounds of harsh sanctions on Tehran.
On the anniversary of the US withdrawal, Iran scaled back parts of its commitments as per paragraph 36 of JCPOA that provides a mechanism to resolve disputes when parties believe other signatories are not fulfilling their obligations, Financial Tribune reported.
"We have NOT violated the #JCPOA. Para 36 of the accord illustrates why: We triggered & exhausted para 36 after US withdrawal," Zarif posted on his Twitter account, along with the text of the paragraph.
Other signatories that remained committed had vowed to make up for the economic effects of US restrictions.
The European Union introduced a payment channel called INSTEX (Instrument in Support of Trade Exchanges) to bypass the sanctions and facilitate trade with Iran.
As the process of activating the mechanism faced a long delay, Iran reduced its commitment and gave a 60-day deadline to EU to deliver on its promises.
France, Britain and Germany (E3), which had taken joint responsibility of the mechanism, announced its successful implementation at a meeting of the JCPOA Joint Commission on Friday, not long before the July 8 deadline.
Nevertheless, it only allows the trade of non-sanctioned goods and with Europe for now.
Iran said the last-ditch effort did not meet its expectations and was not enough to stop it from scaling back its compliance.
On Monday, Iran announced that it had surpassed the 300-kg limit of its enriched uranium stockpile set in the deal, with the International Atomic Energy Agency confirming the news.
Zarif, however, said the measures could be reversed once Iran's expectations are met.
"We gave E3+2 a few weeks while reserving our right. We finally took action after 60 weeks [since the US withdrawal]. As soon as E3 abide by their obligations, we'll reverse," he tweeted, referring to the three European countries, plus Russia and China.
International Reaction
Exceeding the limit sparked widespread reaction from the world.
The European Union urged Iran "to reverse this step and to refrain from further measures that undermine the nuclear deal", spokeswoman for EU foreign policy chief, Federica Mogherini, said.
Maja Kocijancic underlined that Europe "remains fully committed to the agreement as long as Iran continues to fully implement its nuclear commitments", AP reported.
France cautioned Iran on Tuesday against carrying out any further measures that would undermine the deal.
French President Emmanuel Macron said in a statement that he recalled "his attachment to the full respect of the 2015 nuclear accord and asks Iran to reverse without delay this excess, as well as to avoid all extra measures that would put into question its nuclear commitments".
The statement added that Macron would take steps in the coming days to ensure Iran meets its obligations and continues to benefit from the economic advantages of the deal, Reuters reported.
British Foreign Minister Jeremy Hunt said he was "deeply worried" by the announcement, reiterating in a tweet that the "UK remains committed to making the deal work and using all diplomatic tools to de-escalate regional tensions."
"I urge Iran to avoid any further steps away from JCPOA and come back into compliance."
A German Foreign Ministry source said that Berlin is very concerned by Iran's step, calling on Iran "to reverse this step and not to further undermine the nuclear agreement".
Russia's top diplomat on Tuesday urged Iran to fulfill its obligations under its nuclear deal with world powers while calling on Europe to offer relief from US sanctions.
Sergey Lavrov called on Tehran to "show restraint, not yield to emotions" and observe provisions of the deal, AP reported.
China has expressed regret over Iran's move, but said Washington's pressure campaign is the root cause of tensions.
Foreign Ministry Spokesman Geng Shuang told reporters on Tuesday that Beijing remains committed to JCPOA, urging all parties to exercise restraint and safeguard the agreement to "avoid escalating tensions".
UN Secretary-General Antonio Guterres appealed to Iran to stick to its commitments under the nuclear deal and address differences through a dispute mechanism, his spokesman said.
“It is essential that this issue, like other issues related to the implementation of the plan, be addressed through the mechanisms established in the JCPOA,” UN Spokesman Stephane Dujarric said, AFP reported.
The White House said it would continue to apply "maximum pressure" on Iran "until its leaders alter their course of action".
"The United States and its allies will never allow Iran to develop nuclear weapons [an objective Tehran says has never pursued]," a statement from White House Press Secretary Stephanie Grisham said, calling it "a mistake under the Iran nuclear deal to allow Iran to enrich uranium at any level".