there wasn't a policy for it. Arab forces would apparently even send out warnings to Israeli civilians that they would be fighting in the area so that the civilians could steer clear.

Because civilians (especially children, the elderly, and the disabled) are all off limits in Islam. There's a massive list of rules Muslims have to abide by when conducting war and the Koran is very explicit about what those rules are. Whatever else they may be, theocratic Muslim governments had better behavior compared to their Christian opponents during the crusades. It's why there was never a counter offensive into Europe. Doing so was forbidden.