Do I , as a dad, have a right to demand that my child return to Israel where he lives with his mother, if she is a single foreign national? He stays with me at weekends and during holidays.

Yes! If you are the child's biological father, under Israeli law, then you have shared,  parental decision making rights, equal to those of  the mother, as the child's natural guardian, including about where the child should live. If the child is habitually resident in Israel, the mother cannot unilaterally impose a change in the minor's place of residence by relocating permanently overseas with the child, against your will. If she does, you are entitled to bring child abduction proceedings overseas, for the minor's return. 

It is easier if you are already formally registered as the child's biological father, and listed as such in his/her birth certificate, but  it is also still possible, even if paternity is not formally registered.