I have unfortunately not been able to find many critical reactions to HAREM. The following are just a few I found online. I will add more in the future as I find them.
"It is hard not to be impressed by the single-mindedness of Joffé who, with only a few shorts to his credit, garnered $10 million, Kinski and Kingsley, and made his own movie...What might have been an intriguing clash of cultures soon dissipates into a listless drama of will they/won't they, until the Tragic Irony of the finale falls completely flat. Fine credentials (attractive decor by Trauner, delicate photography by De Santis) but little inspiration."
"This film's two well-known stars -- Nastassja Kinski as Diane, a sophisticated trainee on the New York Stock Exchange, and Ben Kingsley as Selim an Arab mogul -- are hard-put to bring life into this beautifully photographed but under scripted romantic drama...it is an interesting role reversal, Diane has no qualms about bedding down an attractive man, but Selim's harem is purely decorative -- he does not share her cavalier view of sexual relationships. The twist is that Selim is not really that bad -- in spite of the fact that he has kidnapped the girl, he actually feels compelled to uphold a time-honored tradition that he doesn't really believe. Selim is an aesthete who wants to embrace the ways of the Western world."
-Eleanor Mannikka, All Movie Guide-
"Some years after graduating from the French film academy IDHEC, Joffé made his big screen debut with a lavish but ill-conceived English language film called "Harem" (1985), in which a lonely Arab prince (Ben Kingsley) kidnaps a woman (Nastassja Kinski) off the streets of New York in order to introduce her to a different lifestyle, against her will. The movie wasn't very good, but over a million people went to see it."
-Lisa Nesselson, ArthurJoffe.com-
The clipping presented at the top is available at the official website for Arthur Joffe. Unfortunately there isn't a lot of information on HAREM there either.