Even with pesticides its hard to get rid of - in glasshouses, you can release a predatory wasp which eats them - this is available to buy.

Daily vigorous spraying with water can work, but may not be practical in a dry country like Israel. Soapy water is a little more effective. Pyrethrins work, but are falling out of favor with organic gardeners. Are Green Lacewings available in Israel? They are effective once their populations build up.

Hi Moshe, try dust from clay granular cat litter mixed with water and sprayed onto the plants. The clay dust cuts through the insects shell (so I've read).
I don't know if you can use this spray on foodstuff.

Another thing that I just remembered: get plastic 5 in. x 7 in. cards, spray paint them bright yellow, give them a medium-thin coating of petroleum jelly, and tack them up or hang them from branches near the affected plants. The whiteflies will be attracted to the yellow color, and will get stuck to the jelly. It doesn't eliminate them all, but it helps keep the numbers down--also helps with aphids, leafhoppers, and the flying forms of scale and mealybug.