Tehran - Tens of thousands joined pro-Palestinian rallies in Tehran on Friday, as the annual Quds Day protests take on broader meaning for a region mired in bitter disputes and war.Israel and its perceived supporters in the US and Britain are still the main bogeymen of the Quds (Jerusalem) Day protests, which saw thousands more rally across Iran and in allied countries.But the focus has also turned to the deepening rivalry with Saudi Arabia and jihadists such as the Islamic State (IS) group.Sajad Saber, a 24-year-old student, said it was the first time he had attended the rally in Tehran – triggered by the death of a friend who had gone to fight in Syria."[He] was my buddy and lived in our neighbourhood. He was killed by Daesh recently in Aleppo," said Saber, using the Arabic name for ISIS.Iran is fighting ISIS and other jihadist groups in Syria as part of its support for the regime of Bashar Assad.Huge groups of protesters converged on Tehran University under a blistering summer sun.Many - from young children to elderly women - sported red bandanas with "I love fighting Israel" written on them.President Hassan Rouhani, attending the rally, said regional conflicts were making it increasingly difficult to address the Palestinian issue."Today, due to the divisions in the Islamic world, the presence of takfiris (Sunni extremists) and terrorists in the region... we are far away from the ideal of liberating Palestine," he told state TV, calling for greater unity between Muslims.Many in Iran see these divisions as part of a deliberate conspiracy."Daesh is the creation of Israel. They want Muslims to fight each other and Palestine to be forgotten," said Ali Kotobi, a 63-year-old Iranian born in Iraq, who said his cousins were currently fighting ISIS across the border.'Dogs of America'However, much of the vitriol at the protests was also turned on Iran's main regional rival, Saudi Arabia.Tensions between the two powers have plummeted over their support for opposing sides in wars in Yemen and Syria.They have been further soured by the failure to agree on terms for Iranian pilgrims to visit Saudi Arabia for the annual hajj in September.One elderly man at Friday's rally led a group in shouting "Damned House of Saud, dogs of America!" in reference to the leaders of Sunni-ruled Saudi Arabia.One group carried a fake coffin featuring Saudi Arabia's leaders and slogans against Daesh Sunni extremists.Opposition to Israel and support for the Palestinian cause has been a central issue for the Islamic republic since it took power in 1979.Quds Day was inaugurated by the late revolutionary leader Ayatollah Ruhollah Khomeini, and has become a popular way for the Iranian government to rally the faithful."We ousted the Shah with these slogans," said Mostafa Mokhtari, a 43-year-old electrical engineer, referring to the Islamic revolution of 1979 that ended the rule of the US-backed Shah."If all the Muslims of the world keep saying this, we can destroy the Zionist regime."