Musa Abu Marzooq, a senior Hamas leader, said in a press statement that closing the crossings is irresponsible and the justification for the closure is "totally rejected", Xinhua reported.
"Imposing these measures on the ground is a clear violation of what has been agreed upon... What is needed is to keep these crossings permanently opened to help the process of reconstruction," Abu Marzooq said.
Israeli Radio and Palestinian officials confirmed Sunday that Israel closed down the two main crossing points with the Gaza Strip, including Erez used for individuals' movement and Kerem Shalom used for goods' import and export.
Abu Marzooq blamed the Palestinian National Authority for not caring about the Israeli measures imposed on the Gaza Strip, stressing that the closure is "a collective punishment and violate the international law".
Israel Radio has earlier reported that Israel decided to close the two main crossing points with the Gaza Strip after anonymous militants fired two projectiles from the territory into southern Israel.
It's the first time that Israel has closed the crossing points with the Gaza Strip since the end of the latest 50-day Israeli military offensive on the enclave this summer.