Ban said in a statement issued by his spokesman that he is deeply disappointed that the parties were unable to agree to an extension of the ceasefire, which expired at 8 am local time today.
"The Secretary-General urges the parties to swiftly find a way back to respect of the humanitarian ceasefire and to continue negotiations in Cairo to reach a durable ceasefire," the statement said.
"The extension of the ceasefire is absolutely essential for talks to progress and to address the underlying issues of the crisis as soon as possible," the statement said adding that Ban firmly calls on the parties not to resort to further military action that "can only exacerbate the already appalling humanitarian situation in Gaza".
Four weeks of fighting in the Gaza Strip has killed 1,875 Palestinians and 67 Israelis and left nearly half of Gaza's 1.8 million people displaced.
It was the third deadly attack by the Israeli military on a UN school sheltering Palestinians during the conflict that started on July 8.
Addressing the 193-nation UN General Assembly on August 6, Ban said the United Nations is ready to help rebuild Gaza for the last time as the "senseless cycle of suffering in Gaza and the West Bank, as well as in Israel must end".
He said both the Israelis and the Palestinians are putting all of the international community's citizens "always at unease and concerned, looking helplessly at many people being killed".
