A Palestinian man and his Jewish bride-to-be are facing hostile protests in the Israeli town of Rishon Letzion after Israel's high court refused their application to ban demonstrations outside their wedding reception.

Mahmoud Mansour, 26, a Palestinian from Jaffa, has had to hire dozens of security guards after an anti-Arab group, Lehava, published details of his wedding reception online and called for Israelis to come and picket the wedding hall.

The group, which campaigns against assimilation between Jews and Arabs in Israel, is angry that Mansour's bride-to-be, Moral Malka, 23, is Jewish, although local media reported that she has already converted to Islam and the couple have had an Islamic wedding.

"We've been together for five years, but we've never encountered such racism. I always knew there were racists, but as long as you're not affected by it, until you feel it in your own body, you don't know what it is," Mansour told Haaretz on Sunday.

"If it were someone from her family, I would understand, but these people aren't related. Why do they care? Why are they getting involved? If they think they'll get us to give up on each other, it won't happen."

He said that hiring the security guards had cost over $4,000 (£2,400), half of which was being paid for by the wedding hall, but the remainder the couple had to find themselves. The court decided that protesters would be allowed to picket the wedding, but only at a distance of 200m.

The wedding has become a national issue – drawing comment from even the president on Sunday – underscoring the strength of feeling following Israel's two-month confrontation with Hamas. On Sunday, peace talks in Cairo inched forward but there was no sign of imminent agreement.

Lehava, which campaigns under the slogan of 'saving the daughters of Israel', was revealed to have links with the Israeli government in a 2011 investigation by Haaretz, receiving up to $175,000 per year from the state, over half of its operational budget.

In 2012 the group distributed flyers in east Jerusalem warning Arabs not to visit the mostly Jewish western side of the city, and has campaigned against Jews and Arabs mixing on beaches and Jewish landlords renting to Arabs.

On Sunday's wedding, the group said: "Please come with positive energy and bring loudspeakers and horns. We will ask our sister to return home with us to the Jewish people who are waiting for her," reported Israeli news site Arutz Sheva.

Other Orthodox Jewish groups have also entered the fray. Yad L'Achim, another group that campaigns against Jewish and Arab assimilation in Israel posted a blurred picture of the bride on its Facebook site, calling on Jews to write to her and plead with her not to go ahead with the wedding.

The page, published on 13 August, has got over 2,000 likes and over 4,000 people have written responses asking the bride to cancel the reception and leave her husband.

Speaking to Haaretz, however, Mansour said he had also received many letters of support. "We feel great, and that really gives us strength. They think they'll break us, but we can't be broken. The opposite is true – we're getting stronger," Mansour said.

"The wedding will go on as planned – it will be great. I'm not worried, but it's troubling that on this day, which everyone waits for their whole life, the happiest day of their life, I have to go to court. It's sad that such things happen in this country."