UN Secretary-General Ban Ki- moon has met with Israeli President Shimon Peres.   After the meeting, held here last night, Ki-moon called and both Israeli and Palestinian officials to avoid undermining peace negotiations and work ardently to reach a peace agreement. For his part, Peres praised the peace efforts conducted by Palestinian and Israeli officials. He added that peace negotiations must be the priority for both administrations. The UN chief is on a middle east tour which he so far included Jordan and Palestinian territory. He met with King Abdullah II of Jordan and Palestinian President Mahmoud Abbas