The struggling Volkswagen-backed club said in a statement that Ismael was leaving "with immediate effect" and that a new coach would be named soon.
Robben, 33, joined Munich from Real Madrid in 2009 and last month signed a contract extension until 2018.
Hoffenheim recovered from the concession of an early goal to take a point from a 1-1 draw at Schalke.
Berlin police made nearly 100 arrests on Saturday when Hertha Berlin and Eintracht Frankfurt supporters clashed violently before their Bundesliga game
Borussia Dortmund boss Thomas Tuchel says he doesn't want striker Pierre-Emerick Aubameyang to overthink his game after he scored twice on Saturday.
Bayern Munich kept their dominant form rolling with an eight-goal thrashing of Hamburg.