Officials in Israel said that there have been up to 44 million cyber attacks on government websites since the beginning of the military campaign in Gaza Wednesday.
"This is an unprecedented attack," Finance Minister Yuval Steinitz told reporters said AFP.
"All the attacks were thwarted except for one, which targeted a specific website that was down for six or seven minutes," he added.
The Finance minister described the attack as a "second front" in the war.
GlobalPost has already reported on a declarationmade by the hacker group Anonymous to fight a cyber war with Israel over its offensive in Gaza.
The group was able to take down several websites, including that of an Israel defence and security company and the Philippine Embassy in Israel.
The hacker group said that in all it took down 700 Israel private and public websites, said AFP.
The group also said that it leaked e-mail and passwords from Israel-based websites, said the Washington Post.
It is unlikely all of the current attacks were by Anonymous alone.
"This is an unprecedented attack, and our success has been greater than we anticipated," Steinitz said, according to Sky News.
The conflict has been waged online, almost more than it has has been on the ground.
Twitter and Facebook have seen furious amounts of arguing between the two opposing sides, while both Hamas and Israel have increasingly used social media to taunt one another, said GlobalPost.