IRGC chief Hossein Salami issued new threats to Israel on Thursday, warning the country, "Don't count on THAAD," Saudi media site Al-Hadath reported.
The comments come as Iran awaits Israeli retaliation for Iran's aerial attack earlier this month.
"Every time you fire a projectile, we will fire more than you," he reportedly said.
The US military has rushed its advanced anti-missile system to Israel, and it is now "in place," US Defense Secretary Lloyd Austin said on Monday.
Austin declined to say whether the Terminal High Altitude Area Defense system or THAAD was operational. But he added: "We have the ability to put it into operation very quickly, and we're on pace with our expectations."
Reuters contributed to this report.