Thousands of supporters, including fighters from the party's Al-Quds Brigades military wing, took part in the event in the Palestinian enclave bordering Israel.
Islamic Jihad leader Ramadan Shalah spoke via a video link, using his speech to accuse some Arab countries of abandoning the Palestinian cause.
"If the Arabs turn their backs on Palestine and embrace Israel, they can no longer condemn the resistance for taking support from Iran," Shalah said, without naming any countries.
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"(Iran) is the only country which commits to the unending support of the Palestinian cause."
He also called on Palestinian president Mahmud Abbas to abandon the Oslo peace accords signed with Israel in the early 1990s, which were meant to lead to an independent Palestinian state.
Hamas, another Islamist movement, runs Gaza but has a long-term alliance with Islamic Jihad.
Hamas has been in conflict with Abbas's Fatah movement, which runs the occupied West Bank, since 2007, with multiple attempts at reconciliation faltering.
Shalah on Friday called for all Palestinian factions to come together for a "national dialogue".