Foreign ministry spokesman Artur Dmochowski told reporters that the ambassador, Rolf Nikel, was expected for a meeting on Monday morning.
Dmochowski refused to say what comments had caused offence and which German politician had uttered them.
Relations between Berlin and Warsaw have been strained since the conservative Law and Justice party (PiS) returned to power in Poland in October.
The eurosceptic party has said it will financially support EU efforts to tackle the refugee crisis, but has made it clear Poland would not take in migrants.
The stance has put it on a collision course with Germany, which took in 1.1 million asylum-seekers last year -- the largest group among them coming from Syria -- and has called on all EU members to accept their fair share.
Last month, Waszczykowski retorted sharply to accusations against Warsaw over its refusal and questioned Germany's stance on eastern Europe.
"When did Germany let Polish citizens work in Germany after we joined the EU in 2004? After seven years. Why did no one speak of a lack of solidarity then?" Waszczykowski said at the time.
"Today Germany is taking in one million Syrians, no problem, (yet they are) people from another continent," he told the Berliner Zeitung in an interview.
Warsaw was also irked in December when European Parliament President Martin Schulz, a German Social Democrat, compared the political situation in Poland to a "coup".
Story continues below…
Polish Prime Minister Beata Szydlo demanded an apology.
Several German and other European politicians have also voiced concern over the Polish government's recent media and justice reforms, seeing in them an erosion of liberties.