Erdoğan, addressing his deputies in a parliamentary group meeting on Tuesday, said Israel is undermining peace and international law in the region and committing ethnic cleansing.
“Israel is occupying Palestinian lands step by step,” Erdoğan said, adding that Israel is terrorizing the Middle East.
The week-old fighting has claimed the lives of 113 Palestinians, including 54 civilians. The operation was in response to Hamas pounding Israeli towns with rockets. Three Israeli civilians have also been killed in the latest offensive, which started with Israel's killing of Hamas' military chief.
Israel, the US and other Western powers consider Hamas a terrorist group and have asked Hamas to end its rocket attacks against Israel, stressing Israel's right to self-defense.
“No state in the West can claim that Israel is exercising self-defense,” Erdoğan said in a heated speech, adding that Israel's actions amount to terrorizing the Middle East.
He described Hamas' defiance as legitimate against what he called Israel's “occupation and ethnic cleansing.”
Israel's declared goal is to deplete Gaza's arsenal and press Hamas into stopping cross-border rocket fire that has bedeviled Israeli border towns for years and is now displaying a greater range, putting Tel Aviv and Jerusalem in the crosshairs.
The last Gaza war, a three-week Israeli blitz and invasion over the New Year of 2008-09, killed 1,400 Palestinians, mostly civilians. Thirteen Israelis died in the conflict.
Erdoğan also slammed the UN Security Council filibuster that failed to propose any solution for the escalating Gaza conflict.
The Security Council held heated closed-door negotiations on Monday on a possible statement, but diplomats said a sticking point was that the text did not mention Hamas missile attacks on Israel. Israel said it was these attacks that prompted its major offensive against the fighters in Gaza.
A resolution is passed when it receives nine votes in favor and no vetoes by the five permanent council members -- Russia, China, Britain, the United States and France. Some diplomats said a vote on the Russian resolution would likely be tight and could force a veto by the United States.
The Security Council is generally deadlocked on the Israeli-Palestinian conflict, which UN diplomats say is due to the United States' determination to protect its close ally Israel. The council held an emergency meeting on Wednesday to discuss the Israeli strikes on Gaza but took no action.
Erdoğan said he has completely lost his trust in the Security Council. "Where is your justice?" Erdoğan asked rhetorically.