Ministers said the government would fast-track legislation allowing the prosecution of people acting as proxies of a state-sponsored group, so they can be dealt with in the same way as spies for foreign intelligence services.
British police and security officials have warned that Iran has increasingly sought to use criminal proxies to carry out hostile activity, and that Russia and China have done the same.
A pro-Iranian government group has claimed responsibility for some recent attacks.
In March, two men were charged under Britain's existing National Security Act with being tasked by Iran to carry out hostile surveillance, and in 2025 three men were convicted of an arson attack on Ukraine-linked businesses.
Officials say Moscow turned to criminals or those with existing grievances following the expulsion of Russian spies over the 2018 poisoning of Russian double agent Sergei Skripal.
Such accusations have been rejected by Moscow, Beijing and Tehran, which say they are politically motivated.
Thursday's announcement of new powers, and additional funding for security, follows criticism of Britain from Jewish community leaders and the Israeli government after a spate of recent attacks, mostly arson, on Jewish targets in London.
The recent incidents are part of a rising number of anti-Semitic attacks in Britain and worldwide since the October 2023 Hamas assault on Israel that triggered the war in Gaza.
Jewish leaders in Britain have said regular, large marches in support of Gaza have created a more hostile environment in the capital, where they say anti-Semitism is increasingly common.
In October 2025, two people were killed after an attack at a synagogue in the northern English city of Manchester.
A week later, two men went on trial over a plot to kill hundreds in an Islamic State-inspired gun rampage against the Jewish community.
They were found guilty in December, just more than a week after a mass shooting at a Jewish Hanukkah celebration on Australia's Bondi Beach.
Britain's independent reviewer of terrorism legislation, Jonathan Hall, told the BBC the British attacks had become "the biggest national security emergency" since 2017, when there was a string of high-profile attacks.
Interior minister Shabana Mahmood said Stg25 million ($A47 million) in additional funding would pay for more protective security for the country's synagogues, schools, places of worship and community centres, boosting police numbers in areas with a large Jewish community.
"We are seeing a huge increase in anti-Semitism, and that's why the government's work on education and stamping out anti-Semitism across other parts of the public sector is also an incredibly important part of this picture," Mahmood said.
She did not say the legislation would be used against the Islamic Revolutionary Guard Corps, but told Sky News: "I expect to be making decisions in the very near future about the groups that we will be designating as state-linked."
