A north shore cafe has closed its popular playroom after parents and their children continued to "display deplorable manners", including leaving dirty nappies on dining tables, the owners say.

John and Claudette Osterberg, owners of Black Mocha in Turramurra, broke the news to customers via a Facebook post on Tuesday that outlined some of the behaviour they say forced the playroom's closure.

John and Claudette Osterberg at their cafe, Black Mocha, at Turramurra. Credit:Peter Rae

"Black Mocha is not a crèche, a play centre, your home, or an open park; it is a café. Just because the café provides toilets, a change table, playroom & a kids menu it, does not make it a kid's cafe," they wrote in the post.

The offending behaviour included: