Reflecting on Yom Ha'atzmaut this week, Mr Wegier maintained that Israel remained an integral part of British Jewish identity, adding that those who took a step back alienated themselves from other aspects of communal life.
But he warned of a "big challenge" in convincing younger Jews to engage with Israel.
Mr Wegier also suggested that the controversy surrounding Labour's antisemitism crisis, and the conflation between antisemitism and anti-Zionism, had bolstered the community's attachment to Israel.
"When the current conversation broke out, a lot of Jews became very defensive around Israel," he said.
"Personally, I do not think you can separate 'Jewish' from 'Israel'. I do not think there is a difference between anti -Zionism and antisemitism.
"The idea that the Jews as a people are not entitled to self-determination - which is what Zionism is - is in my view an antisemitic claim.
"We want people to be proud of their Jewish identity, of their Zionist identity. I'm aware that there is a minority of Jews who don't buy that argument. We have to respectfully disagree with them."
UJIA is the leading provider in Britain of educational programmes in Israel.
Mr Wegier began work in his role at the charity in 2012. A former chairman of the FZY youth movement and youth worker for the Jewish Agency in the UK, the father-of-three made aliyah in 1990.
Now, Mr Wegier recognises that Israeli government policies have alienated certain sections of the UK community - especially young people.
The issue of the "settlements divides British Jews, in the same way Israelis are divided on the issue", he said, emphasising that UJIA was a non-political organisation. "I absolutely see that the politics of Israel is a divisive factor. You would really have to be an ostrich not to see that.
"Some people react to the politics of Israel and become even more engaged; they want to be more involved in campuses and fighting boycotts. Other people lower their Israel engagement," he added.
"One of the things that deeply disturbs me is when I've spoken to young people who have grown up in the Jewish community and were involved in their shul or youth group; then they go to university and say 'I want to spend my time on campus studying and partying; I'm not going to be such a big Jewish activist'.
"That to me is a big challenge. I want to confront them and turn that around.
"I want to be careful about generalising, but people who walk away from Israel sometimes are walking away from other aspects of Jewish life."
Mr Wegier said UJIA could no longer take the younger generation's support of Israel for granted.
He said: "The assumption one could make 30 years ago, one cannot make today. The point I always make is you can't reduce Israel to a political argument. Israel is much broader, much bigger than the political argument.
"The culture, the economy, the hi-tech, that is the language we want people to engage with in Israel - way beyond just thinking about the conflict, the peace process, the territory, whatever it might be."
Mr Wegier said there was no data to prove whether there was a decline in support for Israel among young Jews.
But the Young UJIA department has been increased from one to three staff members in a bid to strengthen engagement among young people.
The charity also launched the Centre for Israel Engagement, which works with youth movements and schools, the mentoring Jewish Entrepreneurs Network initiative, and doubled funding for youth leadership programmes from £75,000 to £150,000.
Mr Wegier, one of the community's best remunerated chief executives with a salary last year of around £140,000, said he hoped the decision to allow people to spend a gap year in Israel on the Birthright programme - even if they had been part of an Israel youth movement before - would also boost engagement.
UJIA, which receives 99 per cent of its donations from the UK Jewish community, was looking, he said, to boost financial support from younger Jews, as well as long-standing supporters.
Mr Wegier said 50 per cent of annual funds came from flagship events, 45 per cent from directly speaking to donors and five per cent from legacies.
In the financial year to 2014, that amounted to a voluntary income of £10.4 million.
Of younger donors, Mr Wegier said: "It wouldn't be honest to say we are looking to engage them now so they give in the future. I want them to give now…
"I think a young Jew has a responsibility to give to Jewish charity. Everyone should give according to their ability. It's responsible giving."
UJIA has revamped its group of 15 trustees. It now includes six women. "We have taken a conscious decision that we need to have a trustee board that reflects our Jewish community," he said. "It is a really important statement."
