Assistant Secretary of State for Public Affairs P J Crowley said, "I think it remains an issue of concern that we are continuing to talk to the government of Pakistan about."
US diplomats have been complaining that their officials have not been issued new visas or their visas are not being extended.
Last month the State Department said the issue is being taken up at the highest level.
As the US prepares to increase its aid to Pakistan, it is also planning to increase its embassy staff so as to effectively monitor its civilian aid in the country.
The ties between the two countries were strained last week after a US Consulate vehicle and its employees were detained while travelling in Gwadar.