Could the Iberians have tried to enslave Jews and Moors?
Also, why weren't white slaves used besides the indentured servitude system falling apart after Bacon's Rebellion? Is it because white people sunburn too easily?
I haven't read this yet but it's probably helpful.
I think that it is very improbable. It was not legal to enslave a crown's vassal, and the spanish moors and jews where vassals of the spanish and portuguese crowns. You must find some way to break the feudal contract without legal consequences, and probably the only way to do that is expeling them from the kingdom, as was IOTL (and even in that way there was unrest among a part of non-jew or moor population). Of course, you could find some way to cheat the law, but since the moors and jews were originally in Iberia and not in the other extreme of the world, it's more difficult to do that. They should be enslaved once they are in the Americas.
I think that the key piece here is that the african slaves were more easy to acquire than others. The african slaves market existed before the european expansion, it had been well profited by the different states in the Maghreb and also Iberia in the Middle Age, and was one of the main sources of income for the triangle Tombuktu-Gao-Djenné with the gold, the ivory and some spices that they exchanged for salt and manufactured goods. The portugese expansion in the african coasts changed the center of that transaharian trade to the atlantic coast, but the market was there before them and was one of the region's atractives for the Europeans. The need of workforce in the Americas, obviously, intregated that market in the atlantic circuit and, sadly, expanded it. So, if you have a market that can provide you the slaves that you need and that is yet established, you don't need to look for new sources of slaves.
As Carlton-beach says, there was a two-way street enslaving in the Mediterranean, but most of them where war prissioners or took in coastal raids and piracy actions, so there wasn't a permanent flow of slaves and not in the needed number. And often they didn't need to sell them, but only wait to someone from the other shore paying the ramsom. They were also valuable in the galleys, the dorsal spine of the mediterranean fleets at the time.