The spokesperson did not provide further details on what kind of examination the agency was carrying out.
Lithanua's state cybersecurity body said last week that Xiaomi phones had a built-in ability to detect and censor terms such as "Free Tibet", "Long live Taiwan independence" or "democracy movement".
Xiaomi said on Monday it was engaging a third-party expert to assess the allegations by Lithuania that its smartphones carry built-in censorship capabilities.
The company was not immediately available for comment on the German probe.
Xiaomi emerged as the top smartphone vendor in Europe for the first time in the second quarter of 2021, shipping a record 12.7 million units there, research firm Strategy Analytics said.
Along with other Chinese rivals on the Android operating system, Xiaomi has enjoyed a surge in market share following the enforcement of U.S. sanctions against Huawei Technologies Co Ltd, which crippled its once-dominant smartphone division.
Germany has had security concerns about using technology from Chinese companies such as Huawei in its 5G network rollout after U.S. calls for banning the company, saying its equipment could be used to support Chinese state spying.
(Reporting by Andreas Rinke and Nadine Schimroszik; Writing by Riham Alkousaa; Editing by Thomas Escritt and Alex Richardson)