Hundreds of women, many wearing black chadors or Islamic-style head scarves, carried Palestinian flags and yelled, "Murderer Israel, get out of Palestine!”
A man with a loud speaker warned the Jewish state that it was turning Turkey's 70 million Muslims against it.
"Inshallah (God willing), all of Turkey will show in coming days that it is behind Palestine!" He said.
"Inshallah!" The crowd yelled back.
As protesters streamed out of the Beyazid Mosque after prayers and began to fill the square, police said they estimated 5,000 people had shown up. Later, they downgraded that estimate to 2,000.
The protesters briefly chanted, "Islam will rule the world." Young men wearing checkered scarves wrapped around their faces like Palestinian militants chanted as they burned Israeli flags, and the entire crowd yelled "greetings to Hamas, continue the resistance!"
Police wearing riot gear surrounded the square, but there were no arrests and no violent incidents.
Prime Minister Recep Tayyip Erdogan said Friday that he had contacted Palestinian authorities in an effort to help end the crisis over Israel's military offensive, which began after terrorists captured an Israeli soldier.
Erdogan was widely criticized for inviting Hamas officials to Turkey earlier this year after they won the Palestinian elections. Turkey has friendly ties with both Israel and the Palestinians.
Israel's air force has struck more than 30 targets in Gaza – including the Palestinian Interior Ministry – while thousands of Israeli soldiers backed by tanks have taken up positions in the southern part of the strip.
The top Palestinian diplomat to Turkey, Nabil Marouf, said on Friday that the events in Gaza were "a true holocaust."
'Bush and Olmert are murderers'
In Egypt, thousands rallied in one of Egypt's main mosques Friday protesting Israel's offensive in the Gaza Strip, many calling on Arab governments to take action to protect the Palestinians.
Hundreds of security forces in riot gear lined up alongside Cairo's al-Azhar Mosque during the protest following weekly prayers. But there was no move to crack down on the demonstration, and police commanders said they wanted to avoid a confrontation, even though the protest was organized by one of the government's top rivals, the Muslim Brotherhood.
"Rulers of Arab countries, start jihad (holy war). Allah Akbar (God is great)," shouted a group of men in the mosque, while nearby several dozen women worshippers chanted, "keep our country free and tell the (Israeli) ambassador to leave. We will not be afraid, we will not back down, we will not be silent."
Several small demonstrations were held in other parts of the Arab world. But the weekly Friday prayers at mosques - a frequent launching ground for political protests - did not see a massive outpouring of anger over the Israeli assault in Gaza, sparked by the abduction of an Israeli soldier by Hamas-linked terrorists.
Governments, particularly Egypt's, appeared eager not to enflame sentiments.
Al-Azhar mosque, the most prominent institution in the Sunni Arab world, was packed with more than 3,000 worshippers obviously there for the pro-Palestinian protest after prayers - but the government-appointed cleric conspicuously avoided the topic in his sermon.
"Bush and Olmert are murderers, but no one will say so because they fear the Jews and Israel," Said one Egyptian worshipper, Mahmoud Abu el-Bashir, referring to US President George W. Bush and Prime Minister Ehud Olmert.
"The US supports Egypt with weapons and soldiers, so our government is paralyzed and unable to do anything," The 60-year-old engineer said.
Egypt has taken the forefront of diplomatic efforts to win the release of the Israeli soldier, fearing the crisis
could spiral out of control. Egyptian President Hosni Mubarak said militants had agreed to the soldier's
conditional release. Israeli officials said they had no information on a deal, but one said a planned ground
offensive in Gaza had been delayed to give time to Egyptian mediators.
Some 100 Palestinians staged a sit-in outside the UN building in downtown Beirut Friday to protest the Israeli incursion into Gaza and demanded world action to protect the Palestinians. In Jordan, some 400 Palestinian worshippers marched in the streets of Baqaa refugee camp on the outskirts of Amman.