U.N. Secretary-General Ban Ki-moon is concerned by the level of violence in Gaza but expressed hope that the cease-fire brokered by Egypt will hold, U.N. spokeswoman Michele Montas said Monday. Ban calls on the Palestinian Authority to take the necessary steps to restore law and order, and for all factions to abide by the ceasefire, Montas told reporters. Ban was appreciative of recent mediation efforts and thanked Egypt for its role in the negotiations, Montas said. The secretary-general remains deeply concerned about the disproportionate use of military force by Israel, Montas said. While recognizing Israel's right to defend itself, he calls on Israel to abide by international law and to ensure that its actions do not target civilians or put them at undue risk. Ban also is concerned that Palestinian fighters continue to fire rockets at Israel, Montas said.