Police also urged organisers of a planned pro-Palestinian protest in London this weekend to cancel or postpone the event, saying it would divert police resources needed to protect fearful communities following the attack.
Israel accused Britain of allowing rampant anti-Semitism to spread through its cities and universities since the war in Gaza, and British Jewish leaders said they had long feared an attack as criticism of Israel had spilled over into open hatred of Jews.
Israel repeated that criticism when two men, Adrian Daulby, 53, and Melvin Cravitz, 66, were killed on Thursday by a British man of Syrian descent who drove a car into pedestrians and then began stabbing them outside the Heaton Park Hebrew Congregation Synagogue in the city in northern England.
Police have named the attacker as Jihad al-Shamie, 35, who was shot dead at the scene by armed officers.
Anti-semitism has soared to record levels in Britain since the October 2023 attack by Hamas on Israel and Israel's subsequent war in Gaza, according to the Community Security Trust, which provides security to Jewish organisations across Britain.
Prime Minister Keir Starmer's government has also clashed with Israel over its decision to recognise a Palestinian state.
Britain's interior minister, Shabana Mahmood, said she understood the strength of feeling held by all sides on Gaza but said that must not lead to violence on British streets.
"It is important that we do draw that line between what is happening in the Middle East and events here at home," she said.
She also criticised pro-Palestinian protests that took place hours after the attack in Manchester, calling them un-British and dishonourable, and urged people to show a bit more "humanity and some love towards a community that is grieving".
Mahmood said policing numbers would be increased around Jewish institutions and that the government would do whatever it took to keep the Jewish community safe.
Asked about Israel's criticism, she told the BBC: "There are unacceptable levels of anti-Semitism in this country, but I just want to be clear, the person who is responsible for the attack that took place yesterday is the attacker himself."
The killing has left Britain's Jews reeling, particularly in Manchester, home to the country's largest Jewish community outside London and a highly diverse city.
Many Jewish leaders noted that they were the only faith in Britain that routinely required security at its institutions.
Shortly after the attack, which also left three people seriously injured, around 30 mostly Jewish elderly men were seen emerging from the synagogue.
Wearing white robes or suits and skullcaps, many were in tears, others looked shocked as they searched for family members.
On Friday morning there was a heavy police presence at the scene of the attack, with debris still lying in the street and bunches of flowers being left nearby.Â
Dawud Taj, a 28-year-old from Manchester, said the government should have done a better job at protecting people.
"There's an atmosphere in the air," he told Reuters as he walked to the city centre, "and everything feels a little bit shaky".
