The main problems are threefold - Morocco is not the most densely populated of places and needs its people, so even a successful slave trade would only be able to meet the limited demand of a domestic and luxury slave economy. Locals would outbid outsiders - indeed, IRL by the early 14th century the net direction of the slave trade still went the other way, with Europeans selling Caucasians, Bogumils, Central Asians and the occasional unlucky Catholic or Orthodox Christian to North Africa. Secondly, the potential slave population is composed of Muslims, Jews and Christians. Muslims being enslaved and sold to Christians would have scandalised the local Muslim population, and while such abuses could (and did) go on, they could never be an acknowledged part of the economy. Christians enslaved would ask their freedom once reaching Christian realms, with a similar effect on the other side. And while (as usual) nobody would have too many problems with picking on the Jews, there aren't that many of them to be had. In a pinch you could always catch and circumcise Christians for sale, but again, that's no basis for a formal economy. Finally - Morocco wasn't exactly a savage, war-torn, tribal place. Any slave raid would be met with a competent and painful response. Indeed, when slave raiding in the Mediterranean started up again in earnest, the Christian powers came off second best.
The only thing I could see happening would be the MOroccans spottinga commercial opportunity and importing African slaves for resale to Europe. Again, not likely to do more than feed a limited market.