The Greek defender and Austrian forward needed to be separated by team-mates after the latter took exception to the former's overzealous tackle.
"It was a strong challenge, but these things happen in football," said Schaaf.
"There is a lot of emotions involved and things like this are part and parcel."
Schaaf will now be hoping for similar emotion and engagement at the Coface Arena as his side look to halt their slide down the table, brought about by picking up only two points in their last five games.
"There's no way of avoiding the fact that people are starting to worry," added Schaaf.
"Our situation is exactly the way the league table presents it."
The standings do not make for happy reading in Bremen with just six points currently separating them from the relegation zone.
Mainz coach Thomas Tuchel prefers to look at the league table of the past 10 seasons, which shows Bremen as a regular in the top five and his side nearer to the bottom.
"It's certainly an achievement to be ahead of Bremen," he said on his club's website.
"But we are totally aware that we have to be at our best tomorrow [Saturday].
"There is always a risk against Bremen."
Tuchel has future Bayern Munich defender Jan Kirchhoff back after suspension while Elkin Soto is also fit again.
Aleksandar Ignjovski hopes to be fit to play for Bremen, despite being forced to pull out of Serbia's national team in midweek through injury.