Gates and a lock on the front of the former temple in the Whitechapel area of east London had minor damage, but no one was injured, Metropolitan Police said on Tuesday.
The incident is the latest attack since four ambulances owned by a Jewish charity were torched in March.
Since then, a synagogue was firebombed and other Jewish sites have been targeted in attempted arsons.
Two Jewish men were stabbed on April 29 in what police have called an act of terrorism.
"It is part of a pattern of rising anti-Semitism that has left our Jewish communities feeling frightened, angry and asking whether this country, their home, is safe for them," Starmer told community leaders.
"These disgusting attacks are being made against British Jews. But, make no mistake, this crisis - it is a crisis for all of us."
The number of anti-Semitic incidents reported across the UK has soared since the attack by Hamas-led militants on southern Israel on October 7, 2023, and the subsequent war in Gaza, according to the Community Security Trust charity.
The group recorded 3700 incidents in 2025, up from 1662 in 2022.
The wave of recent attacks have come since the February 28 start of the Iran war and police are looking into whether they are the work of Iranian proxies.
A pro-Iran group calling itself Harakat Ashab al-Yamin al-Islamia - or Islamic Movement of the Companions of the Right - has claimed responsibility for several of the attacks.
It has also admitted being behind incidents in recent months at places of worship, business and financial institutions across Europe, all of which appear to be linked to Jewish or Israeli interests.
"One of the lines of inquiry is whether a foreign state has been behind some of these incidents," Starmer said.
"Our message to Iran, or to any other country that might seek to foment violence, hatred or division in society, is that it will not be tolerated."
Starmer promised to take action to tackle anti-Semitism, including requiring universities to publish the scale of the problem and take steps to stop it.
Arts funding will be withdrawn from anyone promoting anti-Semitism.
Britain raised its terror threat level from substantial to severe - the second-highest on a five-point scale - after the stabbings.
The rating means intelligence agencies consider an attack highly likely in the next six months.
The change was not solely due to the knifings but also "from Islamist and extreme right-wing terrorist threat from individuals and small groups based in the UK", the government said.
