(Adds wounded boy critical, another serious, both 14) JERUSALEM, Dec 26 (Reuters) - A rocket fired on Tuesday from Gaza injured two Israelis, the first to be hurt in a Palestinian attack since a ceasefire began a month ago. A 14-year-old boy was in critical condition and another, also 14, was seriously hurt by the rocket that slammed into a street near a house in the town of Sderot, Leah Malul, a spokeswoman for Barzilai Hospital, said. Israeli Prime Minister Ehud Olmert made plans to convene top decision-makers on Wednesday to weigh a possible Israeli response, an Israeli source and media reports said. "It is clear that Israel's policy of restraint is not open-ended and these rocket attacks must stop," David Baker, an official in Olmert's office, told Reuters. Olmert has come under growing public criticism for failing to retaliate for more than 60 rockets fired since a Nov. 26 truce, while he is also under U.S. and European pressure to keep the ceasefire. Islamic Jihad, a Palestinian militant group, claimed its forces had fired the rocket, and called it retaliation for Israel's continued military raids on its hideouts in the occupied West Bank. The truce had halted Israeli-Palestinian fighting in and near the Gaza Strip, but Israel has continued raids it says are to prevent attacks from being launched from the West Bank. Israel has killed 15 Palestinians since the ceasefire began, all but one in the West Bank. About half were gunmen. (Additional reporting by Nidal al-Mughrabi in Gaza)