Iranians rallied nationwide on Friday in a show of support for Palestinians and to protest against Israel, AFP reports.
Demonstrations were staged in Tehran and more than 700 towns and cities across the country on the last Friday of the Muslim holy fasting month of Ramadan, state television reported.
In the capital, footage showed demonstrators carrying placards saying "Death to Israel" and "Death to America" converging from nine different points on Tehran University in the city centre.
"Quds Day" (Jerusalem Day) is staged annually on the last Friday of Ramadan, but this year's protest came on the 18th day of Israel's campaign against rocket-firing militants in the Gaza Strip.
More than 800 Palestinian Arabs, some of whom are civilians, have been killed in the assault on Gaza and the Islamist Hamas, a key Iran ally.
Projectiles fired into Israel have killed three civilians - two Israelis and a Thai migrant worker - and fighting in and around Gaza has killed 32
Iran does not recognize Israel's existence, and supports Palestinian Islamist terrorism as a regional ally to fight it.
On Thursday, the speaker of Iran's parliament, Ali Larijani, told state television's Arabic service that Tehran had provided Hamas with the technology it has used to rain down rockets on Israel.
"Today, the fighters in Gaza have good capabilities and can meet their own needs for weapons," he said. "But once upon a time, they needed the arms manufacture know-how and we gave it to them."
Supreme leader Ayatollah Ali Khamenei on Wednesday called on the Palestinians to keep fighting Israel and to expand their resistance from Gaza to Judea-Samaria.
Israel accused Iran of supplying Gaza militants with its Fajr-5 missile, which has a range of 75 kilometers (45 miles), for use during that conflict.
The commander of Iran's Revolutionary Guards, General Mohammad Ali Jafari, claimed at the time that it was not the missiles that had been supplied but their technology.