An attack on a Jewish temple is being treated as a religious hate crime.
A window was smashed at the synagogue in north Belfast some time on Friday night or Saturday morning. A replacement window was then smashed on Saturday afternoon or evening.
Suspicions have been raised that the attack is linked to the current situation in Gaza.
Rabbi David Singer said the Jewish community had been left shocked by the attack.
He said: “I think across the community, first of all, it's very sad that it happened.
“I would imagine that there's a certain amount of anger that it could happen, but angry in the sense of frustration, not angry in the sense that they'd want to do anything about it.
“Certainly, it's very sad and very disturbing that Belfast would show its face like this.”
Ulster Unionist leader Mike Nesbitt said it was “totally unacceptable” for places of worship to be targeted.
“The Jewish community have been valuable members of our society for many years,” he said.
“We offered refuge during the Second World War to many fleeing the Holocaust and it is abhorrent that the synagogue has been the target of this hate crime.”
The DUP's North Belfast MP Nigel Dodds said those who attacked the Belfast Synagogue twice over the weekend must be condemned across the community.
Mr Dodds added: “This is a disgraceful and despicable action. Those who have such hatred in their hearts to carry out this attack must be condemned.
“The Jewish community are a long established part of Belfast and have a rich history in the city.
“I trust the police will be able to apprehend those responsible for this latest act of hatred.”
Dan McGinn is originally from the area around the synagogue.
He said: “As someone who grew up in north Belfast among Jewish friends and neighbours, I have to say the attack on the synagogue is disappointing and disgusting.
“I was invited in as a child by my Jewish friends and feel really privileged to have been given an insight. An attack on any place of worship — Jewish, Muslim or Christian — is an outrage in any democratic or non-democratic society.”
Demonstrators holding a rally in support of Gaza clashed with Union flag protesters displaying Israeli flags at Belfast City Hall over the weekend.
There were no reported injuries and no arrests.
Belfast once had a thriving Jewish community but numbers have dwindled in recent decades.
Police are treating the two incidents as a religious hate crime.
They have appealed for anyone who witnessed the attacks or has any information about them to contact them on the non-emergency 101 number.