Iranian lawmakers and commanders issued stark warnings to the United States and its allies on Tuesday, saying any military strike on Syria would lead to a retaliatory attack on Israel fanned by “the flames of outrage.”

The warnings came against a backdrop of rising momentum among Western governments for a military intervention in the Syria conflict over what the United States, Britain, France and others have called undeniable evidence that President Bashar al-Assad’s forces used banned chemical weapons on civilians last week, killing hundreds. Mr. Assad has accused the insurgents who are trying to topple him of using such munitions.

Iran, which itself came under chemical weapons assault by Iraq during its eight-year war in the 1980s, has been a loyal ally of the Syrian government. Iranian hard-liners often say Syria is Iran’s first trench in a potential war with hostile Western powers. Iran has blamed Israel for the conflict in Syria, saying Israel is trying to bring down Mr. Assad.

“In case of a U.S. military strike against Syria, the flames of outrage of the region’s revolutionaries will point toward the Zionist regime,” the semiofficial Fars news agency quoted Mansur Haqiqatpur, an influential member of Parliament, as saying on Tuesday.