US Secretary of State John Kerry has said that in some cases, US spying has gone too far.
Mr Kerry is the most senior Obama administration official to have commented directly on an issue that has upset America's European allies.
He said he will work with the president to prevent further inappropriate acts by the National Security Agency.
His comments come as Asian countries have protested at claims that Australia was involved in a US-led spy network.
China has demanded an explanation of the reports, while Indonesia has summoned the Australian ambassador to Jakarta.
In other developments: Major technology companies including Google, Apple and Yahoo have called for the US government to do more to rein in the NSA's activities. A German MP said ex-US intelligence contractor Edward Snowden is willing to travel to Berlin to help investigations into the alleged surveillance of Angela Merkel's phone. Indonesia's foreign minister said reports that the NSA used Australian embassies to eavesdrop on Asian countries would indicate a "serious breach" of diplomatic rules.
Edward Snowden met German politician Hans-Christian Stroeble in Moscow
In his comments, Mr Kerry also defended the need for increased surveillance, saying it had thwarted terrorist attacks.