Germany's foreign minister said he hopes the US has understood that surveillance of political partners "can have a political price" and is confident it will end monitoring of allied countries' leaderships.
Frank-Walter Steinmeier was quoted as saying in an interview with the weekly Der Spiegel published on Sunday that the task of overcoming differences over US surveillance activities "should not be underestimated".
He added his voice to growing scepticism over a hoped-for "no-spy" accord with the US, saying: "I doubt that a 'no-spy' agreement will get us much further."
Chancellor Angela Merkel's government sought such an accord following revelations about surveillance by the National Security Agency, including allegations Ms Merkel's mobile phone was monitored.
This month, President Barack Obama said there is no country with which Washington has a no-spy agreement.