The player's former girlfriend, who was pregnant at the time, has filed a criminal complaint against him for domestic violence in 2020, with an investigation under way.
The club said it had met the player and his advisors to discuss the matter.
"Nico Schulz has informed us that he will defend himself against these accusations with the help of legal counsel and, in addition, calls for the presumption of innocence to be applied.
"The allegations that have been made -– of which Borussia Dortmund had no knowledge whatsoever until the media reports emerged -– are extremely serious and shocking for BVB," it said in a statement.
"Borussia Dortmund takes them very seriously and distances itself from any form of violence."
The club, which kicked off its Bundesliga season with a 1-0 victory over Bayer Leverkusen on Saturday, said it was unable to take any action at this early stage of the investigation.
"Borussia Dortmund is not party to the proceedings and has no insight whatsoever into the investigation files or the criminal charges that are apparently pending.
"As this is a pending case in its early stages, and the factual and legal situation is extremely unclear to Borussia Dortmund as it stands today, we are not yet able to make any reliable and legally watertight decisions with regard to labour law and disciplinary measures."
The 29-year-old Schulz, who has also played for Hertha Berlin, Hoffenheim and Borussia Moenchengladbach in the Bundesliga, has earned 12 caps for Germany.
