The attacks in solidarity with the Palestinians have in the past succeeded in blocking government sites, including for the ministries of defence and foreign affairs.
"We are prepared for all forms of aggression," an official from the Shin Bet domestic security agency told AFP. "Israel is well-protected."
In the past Israeli governmental and company sites have been shut down; sites have been hijacked to display photos and videos from Anonymous; and data has been pirated and made public, said Meni Barzilai from the University of Tel Aviv's cyber research centre.
With Israel presenting itself as a leader in cyber-security, the stakes in fending off such attacks are particularly high.
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Cyber-security exports reached USD 6 billion in 2014, amounting to eight per cent of a global market estimated at USD 72 billion.
Some 430 companies specialise in the sector in Israel, compared to 250 a decade ago, employing 19,000 people.
The April 7 cyber-attacks were first launched in 2013 and that year timed to coincide with the eve of Holocaust Remembrance Day in the Jewish calendar.