"Cleary we would be concerned about the terrorist groups that would derail that dialogue process," the official said.
Meanwhile, meeting Sharif over dinner Sunday night, Secretary of State John Kerry said "We're very anxious to have a series of high-level, important discussions over the course of the next few days - the Vice President (Joe Biden), the President, tonight's dinner."
"We have a lot to talk about and the relationship with Pakistan could not be more important. On its own, a democracy that is working hard to get its economy moving and deal with insurgency and also important to the regional stability," he said.
Sharif, who last visited Washington in 1999 during the Kargil war before he was overthrown in a coup by Gen Pervez Musharraf, will hold a series of meetings with the top US officials and lawmakers on Capitol Hill.
