He says the network has a system that would isolate any hacking attempt.
Users complained Sunday that they were unable to place or receive calls for hours.
In 2010, another major Israeli cellphone service provider went down for several hours. The cause of that malfunction was never resolved.
Israel has set up a cyber-warfare unit to combat hacking and says it has repelled millions of attempts to cripple websites. Pro-Palestinian activists have successfully hacked government as well as bank and hospital sites in the past.