Tehran has complained that it has not benefited financially from the deal even before Trump's decision to withdraw.
Iran has said it has the option of resuming industrial-scale enrichment now that the US has withdrawn from the deal.
Under the worldwide agreement, Iran agreed to dismantle its nuclear program and be subject to monitoring in exchange for the lifting on global nuclear related sanctions.
Iran's announcement that it is getting ready to expand production of uranium hexafluoride is significant since this is the primary feedstock that goes into the centrifuges that spin to enrich uranium.More news: Guatemala volcano: At least 25 dead, hundreds injured in eruption
Katz addressed Tehran's threat to restart uranium enrichment at an "industrial level" if the 2015 pact falls apart.
"Iran wants to increase the number of militia to 80,000 and to basically conduct a religious campaign in largely Sunni Syria - which is 96% Sunni - to try to convert the Sunni". The prime minister also linked Iran's intervention in the Syrian Civil War and its buildup of military forces there to the Islamic Republic's broader plans for regional conquest in Lebanon and Yemen.
At a press conference following their talk, Ms Merkel said: "Our meeting focused on an global issue, the Iran agreement".
On Sunday, Khamenei's office tweeted what appeared to be an old quote from Iran's top leader that referred to Israel as a "malignant cancerous tumor" that needed to be removed.
The nuclear deal and lifting of punishing nuclear related global sanctions created optimism in Iran after years of economic isolation.
"We support Israel's right to security and have said this to Iran at all times".More news: Apple unveils ARKit 2
"What we are doing does not violate the [2015 nuclear] agreement", he said, adding that a letter was submitted to the IAEA "yesterday regarding the start of certain activities".
The JCPOA allows Iran to pursue a peaceful nuclear program for commercial, medical and industrial purposes in line with global non-proliferation standards.
Merkel said she agreed that Iran's activities in the Middle East were a concern, particularly for Israel's security.
"Iran calls for our destruction, but it's also seeking nuclear weapons to carry out its genocidal design", he said.
The Israeli Embassy in the U.S. responded to Khamenei's colorful language with a gif from the 2004 film "Mean Girls", in which Regina George, played by Rachel McAdams, Cady Heron, played by Lindsay Lohan's character, "Why are you so obsessed with me?"More news: Toure accuses Guardiola of 'not liking African players'