"There are differing voices coming out of Iran, this (Larijani) is the one that we and our EU partners have said would be the appropriate track for responding," Snow said.
Solana handed Larijani the offer June 6 in Tehran and the US has insisted that Iran has "weeks, not months" to reply.
But Iran is calling for for negotiations without any "preconditions" and says it will give its answer August 22.
A senior European diplomat said foreign ministers from the six world powers making the offer had "tentatively agreed" to meet on the eve of a July 15 G8 summit in St. Petersburg, Russia "to make the tough decisions" on how to react to Iran.
