CAIRO, Aug 21 (Reuters) - The Arab League on Sunday condemned Israeli air assaults on the Gaza Strip and said the United Nations must take action to end the attacks, in which 15 people have died. "We issued a statement condemning the Israeli offensive on Gaza ... and Egyptian land," Arab League Secretary-General Nabil Elaraby told reporters in Cairo. "The United Nations has to take procedures to stop the Israeli offensive on Gaza," he said, without giving details of the measures he was urging the U.N. to take. Among those killed in the aeriel attacks were the leader of an armed Palestinian faction and five civilians including three children. Israel launched the strikes after an assault along its border killed eight Israelis on Thursday. (Reporting by Yasmine Saleh; Writing by Tom Pfeiffer)