I'm not sure that "othered" is actually a word, but I know exactly what you mean. However, I don't think that Portia actively does make Morocco feel different to her because of his skin colour: though he clearly admits (from his very first line in the play) that it is an issue that might affect their (proposed) marriage.
Portia doesn't say a great deal to Morocco: and if you compare it to what she says to Aragon, you'll notice she tends to speak briefly, cursorily, to the point. Is this disregard for Morocco or is this just what Portia is like?
One thing is for sure, however. Morocco begins their encounter (and Act 2) with the line "Mislike me not for my complexion". The last line spoken in Act 2 is Portia, after Morocco's exit, and it does indeed "mislike him" for his complexion: "Let all of his complexion choose me so". Clearly Shakespeare wants Portia's reaction to Morocco's skin colour to be considered in this scenes.