U.N. Secretary-General Ban Ki-moon is “deeply concerned” by the violence in Gaza following an Israeli military incursion into the Palestinian territory, U.N. deputy spokeswoman Marie Okabe said Friday. “The secretary-general calls on all parties to do their utmost to protect civilians and uphold international law,” Okabe told reporters. Media reports said Israel used heavy force when it entered Gaza, including tank fire in populated areas, where a number of Palestinian civilians were injured and at last one killed. Israel also launched missiles into the territory, targeting Hamas militants, according to reports. An estimated 11 militants were killed during the Israeli incursion. “Calm must be restored in order to focus all energies on finding a just and lasting peace in the Middle East,” said Okabe. She added that Palestinians must stop firing rockets into Israel.