"The Islamic republic welcomes any action that serves to decrease arms races," it quoted foreign ministry spokesman Hassan Ghashghavi as saying.
US President Barack Obama last week announced he would shelve plans to site parts of a missile defense shield in Poland and the Czech Republic, and instead deploy more mobile equipment targeting Iran's short- and medium-range missiles.
Ghashghavi called "baseless and unsubstantiated" the idea that the missile plan had been to counter a military threat from Iran.
"The claim that Iran is a missile threat was made by the United States... with political, opportunist and domineering intentions," he said.
Ghashghavi put the original shield plan down to "missile competition between Russia and the United States, and in order to expand the big power's penetration into central European countries."
Washington has expressed concern about advances in Iran's controversial nuclear project to enrich uranium and also in its ballistic missile program.
The United States and other Western powers suspect that Tehran is using its nuclear program as a cover to develop atomic weapons, but Iran insists it is aimed merely at producing civilian nuclear energy.
On Sunday Obama denied that Russian objections had influenced his decision to abandon the shield plans launched by his predecessor's administration.
"Russia had always been paranoid about this, but George Bush was right, this wasn't a threat to them," he said on CBS television show "Face the Nation."
"If the by-product of it is that the Russians feel a little less paranoid and are now willing to work more effectively with us to deal with threats like ballistic missiles from Iran or nuclear development in Iran, you know, then that's a bonus."