Sisi and Abbas, who discussed ways to end the Israeli offensive on the Palestinian enclave, also agreed that Israeli crossings to the besieged Gaza be opened to facilitate movement of people and goods.
It was not clear whether they were also referring to Egypt's Rafah border crossing with Gaza, the only passage that bypasses Israel.
The two leaders met amid intensifying global efforts to end the deadly conflict as Israel and Hamas, the Palestinian Islamist movement that is the main power in Gaza, resumed their strikes, after a brief halt of hostilities Thursday on humanitarian grounds.
"The two presidents agreed on the urgency of holding a donors conference to immediately start rebuilding the Gaza Strip," a statement from the Egyptian presidency said.
It said Sisi and Abbas agreed on the "necessity of an immediate ceasefire" based on an Egyptian plan to stop the conflict that has killed at least 240 Palestinians since Israel launched Operation Protective Edge on July 8 to stamp out rocket fire from Gaza militants.
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One Israeli has died in cross-border rocket fire since the conflict erupted.
Cairo has once again become a diplomatic hub to end the fighting in Gaza after Egypt initially proposed a failed truce without consulting Hamas.
Hamas has laid out a set of conditions, among them the lifting of Israel's eight-year blockade on the Gaza Strip, the opening of the Rafah border crossing with Egypt and the release of Palestinian prisoners Israel has rearrested after freeing them in exchange for kidnapped Israeli soldier Gilad Shalit in 2011.
Abbas met in Cairo on Wednesday Hamas deputy leader Mussa Abu Marzuq, who insisted on changes to the Egyptian truce plan including guarantees on opening border crossings to Gaza.
The initiative called for a return to an Egyptian-brokered 2012 ceasefire that ended eight days of fighting, and loosened border restrictions on goods for the blockaded coastal enclave.
Israel initially accepted the Egyptian initiative but later intensified its air strikes after Hamas rejected the plan, saying it had not been consulted.