The voice claims Anonymous will not stand by as foreign countries remain "silent" and will respond to "heinous crimes against humanity".
Showing footage from the Gaza conflict last summer, which the Israeli Defence Forces (IDF) labelled Operation Protective Edge, the voiceover continued: "We'll erase (Israel) from cyber space as we have every year - 7 April 2015 will be an electronic holocaust."
Anonymous calls young Palestinians the "symbol of freedom, resistance, and hope", telling them to "never give in" and vowing support.
Clips of newly re-elected Prime Minister Benjamin Netanyahu in what appears to be a war briefing room flash up as the voiceover turns to "Zionist entities".
"As promised in previous attacks, we will continue to electronically attack until the people of Palestine are free," the simulated voice says.
"As shown in previous attacks, we will continue to invade and attack your devices, websites and personal data."
It accuses the Israeli government of "endless" human right violations, illegal settlements, the killing of civilians and contraventions of international law.
"This is why elite cyber-squadrons, from around the world, will decide to unite in solidarity, with the Palestinian people, against Israel, as one entity to disrupt and erase Israel from cyberspace," it finishes. "We'll show you on 7 April 2015 what the electronic holocaust means."
Anonymous has launched cyber attacks on Israel in the past, starting in 2012 during the Gaza conflict codenamed Operation Pillar of Defence by the IDF, and most recently last year.
This is the third year an attack will happen on 7 April, which comes just over a week before Israel's Holocaust Memorial Day, known as Yom HaShoah.
Benjamin T Decker, a senior intelligence analyst at Tel Aviv-based risk consultancy The Levantine Group, told Newsweek that Israeli authorities do not consider Anonymous a serious threat after four years of "posturing".
"As the years have progressed we have seen that, despite their increasing sophistication in hacking techniques, we have seen less damage against Israeli cyber-infrastructures, largely due to Israel's pioneering of most cyber-warfare tactics, both offensive and defensive," he said.
But there have been differing claims about the attacks' impact. According to Anonymous, #Op_Israel in 2013 caused $3 billion (£2 billion) worth of damage to Israel and targeted more than 100,000 websites, 40,000 Facebook pages, 5,000 Twitter accounts and 30,000 Israeli bank accounts, Haaretz reported.
The government insisted there was no major disruption, although attacks blocked websites and resulted in officials' personal data and contact details being posted online.
Other hacks have targeted websites belonging to Mossad, the IDF, Bank of Jerusalem and Foreign Ministry, making them unavailable.
To see "Anonymous Message to Israel" Click here
- Independent
