WASHINGTON — Iran has invited Russia, China and several European Union members to visit its nuclear facilities this month, but pointedly snubbed the United States, European diplomats said on Monday.

Tehran confirmed on Tuesday that it had offered the invitation to show what Ramin Mehmanparast, an Iranian Foreign Ministry spokesman, called transparency and “Tehran’s goodwill” on its nuclear program.

The invitation — which seemed calculated to divide the alliance of nations opposed to Iran’s nuclear ambitions before the next round of negotiations over the program — was swiftly dismissed by the United States.

“It’s a clever ploy, but it’s not a substitute for Iran’s responsibilities to the I.A.E.A.,” said the State Department spokesman, Philip J. Crowley, referring to the International Atomic Energy Agency, which has been locked in an increasingly tense standoff with the Iranian government over its enrichment of uranium.