The Group of Seven countries on Friday urged Iran to "cease and reverse" nuclear escalations and stop continuing uranium enrichment activities that have no credible civilian justifications.
The leaders said they would be ready to enforce new measures if Tehran were to transfer ballistic missiles to Russia, according to a communique.
"We urge Tehran to cease and reverse nuclear escalations, and stop the continuing uranium enrichment activities that have no credible civilian justifications," the statement said.
The Middle East has been one of the main discussion points at the two-day summit that started on Thursday at the luxury resort of Borgno Egnazia in southern Italy.
Leaders have highlighted their concern about escalations on the Lebanon-Israel border and endorsed US President Joe Biden's ceasefire plan for Gaza in addition to ramping up support for Ukraine.
The G7 members are the US, UK Canada, France, Germany, Italy and Japan. Several leaders from the Global South, as well as Pope Francis, have been invited for talks on Friday afternoon on Artificial Intelligence.
New generation Iranian centrifuges on display for Iran's National Nuclear Energy Day in Tehran, in April 2021. Iranian Presidency Office / Wana
President Ebrahim Raisi, second right, is accompanied by Atomic Energy Organisation of Iran chief Mohammad Eslami, at Nuclear Technology Day in Tehran in April 2022. Iranian presidency / AFP
Mr Raisi and Mr Eslami at the April 2022 event. Iranian presidency / AFP
The Bushehr Nuclear Power Plant during a visit by Mr Raisi in October 2021. Iranian Presidency / AFP
Iran's Arak Heavy Water Reactor complex, south of the capital Tehran in January 2020. Maxar Technologies / AFP
A satellite image of Iran's Bushehr Nuclear Power Plant in January 2020. Maxar Technologies / AFP
A satellite image of Iran's underground Natanz nuclear site in May 2022. Planet Labs PBC / AP
A satellite image in January 2020 of Iran's Fordow Fuel Enrichment Plant, north-east of the city of Qom. Maxar Technologies / AFP
The Sanjarian nuclear centre, east of Tehran, in May 2021. Maxar Technologies / AFP
The G7 concerns about Iran comes a day after the International Atomic Energy Agency said that Tehran is further expanding its nuclear capacities. The agency's board of governors last week passed a resolution criticising Tehran's lack of co-operation with the UN nuclear watchdog.
The IAEA informed its members that Tehran told the agency it was installing more cascades at the enrichment facilities in Natanz and Fordow.
Iran's military tests the Khaibar ballistic missile. The G7 says it is ready to enforce new measures if Tehran transfer ballistic missiles to Russia. AFP
A cascade is a series of centrifuges, machines used in the process of enriching uranium. A diplomatic source deemed this development as "moderate".
So far, Iran has been enriching uranium in those cascades up to 2 per cent purity. It already enriches uranium up to 60 per cent, a short, technical step away from the weapons grade of 90 per cent.
Tehran did not immediately acknowledge the decision. However, it comes after Iran threatened to take action following a vote earlier this month at the IAEA's board of governors that censured the country for failing to co-operate fully with the agency.
The decision immediately drew criticism from US State Department spokesman Matthew Miller.
“Iran aims to continue expanding its nuclear programme in ways that have no credible peaceful purpose,” Mr Miller said. “These planned actions further undermine Iran’s claims to the contrary. If Iran implements these plans, we will respond accordingly.”
Mr Miller did not elaborate on what steps the US and its allies might take. However, Iran already faces grinding economic sanctions from Washington and others that have deeply cut into its economy and sent its rial currency tumbling over recent years.
The Islamic republic has gradually broken away from its commitments under the nuclear deal it struck with world powers in 2015.
The landmark deal provided Iran with relief from western sanctions in exchange for curbs on its atomic programme, but it fell apart after the unilateral withdrawal of the United States under then-president Donald Trump in 2018.
Efforts to revive the deal have so far failed.
The G7 summit in Italy - in pictures
Pope Francis and national leaders take part in a working session during the G7 summit in Savelletri, Italy. AFP
US President Joe Biden applauds as he listens to Pope Francis. AP
Prime Minister of Italy Giorgia Meloni welcomes Prime Minister of India Narendra Modi. Getty Images
Ms Meloni welcomes Jordan's King Abdullah II. EPA
Ms Meloni welcomes Pope Francis in Savelletri. AFP
Mr Biden and Ms Meloni meet for talks at the G7 summit. AP
German Chancellor Olaf Scholz receives birthday wishes from Mr Biden, European Council President Charles Michel, Ms Meloni, French President Emmanuel Macron, Canadian Prime Minister Justin Trudeau, British Prime Minister Rishi Sunak and European Commission President Ursula von der Leyen on the second day of the G7 summit. Reuters
Mr Sunak attends a meeting with India's Prime Minister Narendra Modi. PA
Mr Biden and Ukrainian President Volodymyr Zelenskyy arrive in Savelletri to sign a security agreement on the sidelines of the G7 summit. AFP
From left, Mr Michel, Mr Sunak, Japanese Prime Minister Fumio Kishida, Mr Macron, Italian President Sergio Mattarella, Ms Meloni, Mr Trudeau, Mr Scholz and Ms von der Leyen arrive for a dinner at Swabian Castle in Brindisi. Reuters
Mr Macron speaks to journalists at the G7. AP
A skydiving demonstration at the San Domenico Golf Course. AFP
The leaders gather to watch a parachute drop at San Domenico Golf Club in Fasano. PA
Ms Meloni arrives at San Domenico Golf Club. Getty Images
Mr Sunak speaks with Mr Zelenskyy on the first day of the G7 summit. AP
Clockwise from bottom left, Mr Michel, Mr Scholz, Mr Trudeau, Mr Macron, Ms Meloni, Mr Biden, Mr Kishida, Mr Sunak and Ms von der Leyen at the summit. AP
Ms Meloni speaks with Mr Biden. AFP
The G7 world leaders pose for a group photo. Getty Images
Ms Meloni greets Mr Biden. Getty Images
Mr Macron is welcomed by Ms Meloni. AFP
Mr Scholz arrives. AP
Mr Sunak is greeted by Ms Meloni at Borgo Egnazia. Getty Images
Ms Meloni arrives on the first day of the G7 summit. Reuters