Hamas was responding to PLO chairman Mahmud Abbas' plea to Palestinian resistance movements to stop firing homemade rockets at Israeli targets because they invited massive Israeli retaliation.
Abbas, also known as Abu Mazin, had said: "It is true that there are some issues regarding rockets, which are useless, but in return there is a grave, a very grave Israeli escalation."
Hasan Yusuf, a leader of the Hamas movement in the West Bank, speaking to Aljazeera from Ram Allah said: "I don't think that Abu Mazin has taken note of the continuing Israeli killings against the Palestinian people.
"The real cause behind the aggression is not the Palestinian resistance, but the Israeli occupation."
Yusuf added: "We should not portray a different picture to the world, and reinforce what they report by saying that the resistance is the aggressor."
Abbas, renewing a call for a ceasefire with Israel, did not demand such attacks stop, but said the raids Israel launches in response to them hinders the election campaign.
"Of course, we renew the call because we believe in peace," he said.
Every nation has the right to
defend itself, says Hamas
"Negotiation is the fundamental way to reach peace between us and the Israelis, in order to implement the road map," he said, referring to a US-backed peace plan, which calls for a halt to violence and the creation of a Palestinian state.
However, according to Hamas, reaching peace can only be attained if Israel ends its illegal occupation of Palestinian lands.
"If the Israeli occupation ends, the detainees are released, and the Palestinian people are given their rights, then the resistance will end. No one would call for any resistance against Israel," Yusuf said.
"We have been calling on the Palestinian leadership for a long time now to form a unified leadership for the Palestinian people to discuss all the issues regarding the Palestinian case and all the matters which serve the welfare and security of the Palestinian people."
He continued: "We had also offered numerous truces and implemented them, but the Israeli occupation forces have rejected them and has continued its aggression and assassinations.
"The Palestinian people are constantly pressured and attacked, with bulldozers, tanks and helicopters, forcing them to resist and defend themselves."
Yusuf said: "All nations in the world have the right to defend themselves when they face aggression and their land is occupied."
Referring to the Qassam rocket attacks, Yusuf said: "The Palestinian people are forced to seek creative methods to resist Israeli aggression and military escalation.
Hamas says armed resistance is
necessary to pressure Israel
"Hamas is not the only movement firing rockets at Israeli towns. All the other factions, including Islamic Jihad, the Popular Committees, al-Aqsa Martyrs Brigades and others do so as well."
Defending the usefulness of the rockets, Yusuf said: "The rocket attacks and the Palestinian resistance are productive and very useful.
"Our experience with the Israelis in the past has been that talks cannot be fruitful unless they are backed by some pressure, which is our resistance on the ground, in response to sustained Israeli aggression."