Boris Johnson and the Prime Minister of Iraq, Adel Abdul Mahdi, have agreed to work to find a diplomatic solution to the crisis in the Persian Gulf, Downing Street has said.
Mr Johnson said Britain will not lament the death of Iranian General Qassem Soleimani, who was assassinated on Iraqi soil on Friday.
Defence Secretary Ben Wallace was called to Number 10 Downing Street, to discuss UK military assets in the region - the deployment of warships to the Strait of Hormuz.
Earlier, Mr Johnson, and the leaders of France and Germany, released a joint statement calling for an easing of tensions in the Gulf.
The statement acknowledges the "negative" role Iran has played in the Gulf region, but also called for all sides to end the "current cycle of violence in Iraq".
"We call on all parties to exercise utmost restraint and responsibility," it read.
"We specifically call on Iran to refrain from further violent action or proliferation, and urge Iran to reverse all measures inconsistent with the JCPOA [the Iran nuclear deal]."
Iran has declared that it will no longer stick to any of the restrictions imposed by the 2015 nuclear deal following the death of one of its most powerful figures.
Under the Joint Comprehensive Plan of Action (JCPOA), struck between Iran and the US, UK, France, Germany, Russia and China, the Middle Eastern country agreed to limit its enrichment of uranium in exchange for the lifting of sanctions.
The statement also recalled "our attachment to the sovereignty and security of Iraq", adding that another crisis "risks jeopardising years of efforts to stabilise Iraq".
Around 400 British troops in Iraq have had their training mission "paused" over safety concerns, amid heightened tensions in the region.
Operation Inherent Resolve - which encompasses US intervention against Islamic State in Iraq and Syria - is prioritising the protection of the Iraqi bases where the troops are stationed, the Combined Joint Task Force has announced.
The leaders' statement added: "We also reaffirm our commitment to continue the fight against Daesh (Islamic State), which remains a high priority.
"The preservation of the Coalition is key in this regard.
"We therefore urge the Iraqi authorities to continue providing the Coalition all the necessary support.
"We stand ready to continue our engagement with all sides in order to contribute to defuse tensions and restore stability to the region."
The Iraqi parliament has voted to clear the country of foreign forces, prompting US President Donald Trump to threaten severe sanctions if 5,200 US troops are expelled.
There are fears that the removal of 5,200 US and 400 UK personnel could lead to a power vacuum and a rise of terror organisations in Iraq.
Last month, experts warned of an Islamic State group (IS) resurgence in the Middle Eastern country.
Mr Johnson is to assemble key ministers to discuss the spiralling crisis in the Middle East, after the assassination of Iran's top military leader.
Efforts to ease tensions come alongside warnings from President Trump threatened to retaliate "perhaps in a disproportionate manner" if Iran strikes a US citizen or target.
The US leader warned that 52 Iranian targets could be hit "very fast and very hard", including "some at a very high level & important to Iran & the Iranian culture".
Targeting culture sites is considered a war crime under international law.
Mr Trump has also stood by the decision to carry out the drone attack without consulting the US Congress.
The UK's Foreign & Commonwealth Office is urging British nationals not to travel to Iraq, fearing the volatility of security there.
In London on Tuesday, a full Cabinet meeting is expected to be called, and a statement delivered to the Commons.