"Iran's weapons of mass destruction and missile programs pose a real threat to regional and global stability and security," said national security spokesman Michael Anton.
"We are working closely with friends and allies and within international groups such as the Missile Technology Control Regime to discourage and prevent Iran's acquisition of medium and long-range missile delivery systems," he said.
The Iranian foreign ministry confirmed Monday that Tehran had conducted a final test of its Shahab-3 ballistic missiles, a move that brings arch-enemy Israel well within range.
The news, which sparked immediate alarm in Israel, came as Iran's clerical leaders dug in on their refusal to allow tougher UN inspections of their civil nuclear program, which Washington says is cover for atomic weapons development.
"We have long made clear our serious concern about Iran's pursuit of weapons of mass destruction and delivery systems," said Anton.