Ancelotti made the gesture as he walked down the tunnel following a 1-1 draw in Berlin in which his side equalised in the 96th minute.
He told German broadcaster ARD he did it "after being spat at".
The Italian former Chelsea boss could still face disciplinary action, but has only been asked to submit a statement.
He has until Tuesday afternoon to do so, and the German FA (DFB) will then decide how to proceed.
A DFB statement read: "The German Football Association's control committee has asked Bayern Munich's coach Carlo Ancelotti for a statement regarding a gesture he allegedly made following the Bundesliga match Hertha BSC versus Bayern Munich.
"He has been given time until Wednesday. The control committee will then decide upon whether to continue investigation."
Robert Lewandowski's equaliser for Bundesliga leaders Bayern came after the indicated five minutes of added time at the Olympiastadion.
Hertha boss Pal Dardai described the extra time played as "Bayern's bonus".
"We always fight until the end, you can't get later than that," said Lewandowski, whose goal was timed at 95 minutes and 57 seconds.
Bayern are five points clear in Germany's top flight, with RB Leipzig, who beat Borussia Monchengladbach 2-1 on Sunday, in second.
Bayern Munich boss Carlo Ancelotti has been asked by the German FA to explain the middle finger gesture he made towards Hertha Berlin fans on Saturday.