Push for talks
"We call upon the Arab leaders to change their minds about these talks and support Palestinian reconciliation instead," Barhoum said.
Hamas said Batran, who will be buried later on Saturday, was a rocket maker and the head of its military wing in central Gaza.
Israel carried out the air strikes "in response" to a rocket attack on the city of Ashkelon on the Mediterranean coast, the Israeli military said in a statement.
Windows of an apartment block were blown out and parked cars were damaged by the rocket, which landed in a residential area, but no one was injured by the blast.
Binyamin Netanyahu, the Israeli prime minister, said "Israel takes the firing on Ashkelon very seriously".
A police spokesman said the rocket fired was a 122mm, Chinese-made Grad, with a heavier payload and greater range than the crude, homemade rockets armed Palestinian group were launching almost daily until Israel's three-week military offensive into Gaza 18 months ago.
No one was injured in the Ashkelon attack but windows were shattered [Reuters]
The rocket attack ended over a year of calm for the Israeli city closest to Gaza.
The Israeli military says it holds Hamas, which governs the coastal Palestinian territory, "solely responsible for terror emanating from the Gaza Strip".
Hamas says it is trying to stop armed groups from firing at Israel, but smaller groups have continued to launch rockets.
Barhoum did not say who was behind the firing of the rocket.
"We do not trust the media of the occupation government. They would fabricate anything to escalate the situation in Gaza," he said.
Israeli media said the government had lodged a protest with the United Nations over the Ashkelon attack.
In a statement, UN Special Co-ordinator Robert Serry said "indiscriminate rocket fire against civilians is completely unacceptable and constitutes a terrorist attack".
Friday's rocket attack and military strikes also came amid a demand from the UN Human Rights Committee in Geneva that Israel lift its military blockade of Gaza – imposed since Hamas seized power there in June 2007 – and let an independent fact-finding mission investigate its raid on an aid flotilla on May 31 in which nine activists were killed by Israeli soldiers.
Israel has recently eased restrictions on imports of food and consumer goods to Gaza but insists that the naval blockade must stay in place to help prevent shipment of weapons to hostile groups in the enclave.