Hamburg have apologised to Werder Bremen captain Frank Baumann after he was struck by a mobile phone battery thrown from the crowd in Sunday's north German derby.
The German FA have opened an investigation after Baumann was struck on the left cheekbone as Bremen celebrated their equaliser in the 2-1 defeat.
The culprit has not yet been identified, but Hamburg chiefs have promised to do all they can to find him.
Board member Katja Kraus told the club's official website: "We can only apologise in the name of HSV. Something like that should of course not happen regardless of emotions.
"We will use every means available to identify the perpetrator."
Head of stadium management at the HSV Arena, Kurt Kragel, added: "We will look again at the video evidence we have from the game. But we are also seeking relevant information from fans."
"I am very sorry this has happened. Fortunately it has not resulted in anything serious," said sporting director Dietmar Beiersdorfer.