Iranian President Hassan Rouhani urged Muslims worldwide on Saturday to unite against the United States and assured Saudis they were "brothers" who had nothing to fear from Tehran.
US President Donald Trump abandoned a landmark 2015 nuclear deal between major powers and Tehran in May and has since reimposed crippling unilateral sanctions.
"What the United States wants of (West Asia) today is enslavement," Rouhani told an Islamic unity conference in Tehran.
Instead of "rolling out the red carpet for criminals," Muslim governments should unite against the United States and "the region's cancerous tumour", Israel, he said.
Rouhani urged Shia Iran's Sunni rival Saudi Arabia to end its dependence on "insulting" US military aid.
"We are ready to defend the Saudi people's interests against terrorism and superpowers with all our might," he said.
"We do not ask $450 billion for it and will not insult you." Riyadh cut diplomatic ties with Tehran in January 2016 after protesters stormed its diplomatic missions in Iran following its execution of a prominent Shia cleric.
It accuses Tehran of fomenting unrest among Shias in the Gulf Arab states and the two governments have supported opposing sides in devastating civil wars in Syria and Yemen.
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