File Photo: Spanish Prime Minister Pedro Sanchez. AP
Last Wednesday, Hamas and Israel agreed on a four-day truce deal starting Friday.
The seven weeks of the war were marked by the deadliest Israeli violence in decades, vast destruction, and displacement across the Gaza Strip.
Visiting the Rafah border crossing between Gaza and Egypt on Friday with Belgian Prime Minister Alexander De Croo, Sanchez said the "indiscriminate killings of innocent civilians" in the Palestinian territory was "completely unacceptable".
Both leaders called for a permanent ceasefire in the war-battered territory, with the Belgian premier also denouncing the destruction in the Gaza Strip as "unacceptable".
The Israeli foreign ministry swiftly summoned the ambassadors of Spain and Belgium for a "harsh rebuke" over comments by the two countries leaders, accusing them of supporting "terrorism".
"Condemning the attacks of a group like Hamas and at the same condemning Israeli indiscriminate killing of Palestinians in Gaza, is not a question of political parties nor of ideology, it is a question of being humane," Sanchez told a gathering of his Socialist party in Madrid to applause from the audience.
Spanish Foreign Minister Jose Manuel Albares told public television on Friday he had called in the Israeli ambassador to lodge a formal protest against the Israeli government's allegations.
Hamas led an offensive on Israel on October 7, killing 1,200 people and seizing around 240 captives, according to Israeli officials.
Since then, Israel has vowed to "crush" and unleashed a withering military campaign on the Gaza Strip which the Palestinian health ministry says has killed nearly 15,000 people, two-thirds of them women and children.
* This story was edited by Ahram Online.