The Reconquista did not succeed in North Africa for two reasons, the Spanish monarch was otherwise occupied in European adventures and the Castillian methods of the Reconquista were not applicable to North African conditions. Aragonese, Catalon and Portuguese navigational technology had for centuries been adequate for the conquest of overseas possessions in the Mediterranean as the acquisition of the Canary Islands, Sicily (occupied by the Crown of Aragon) and other places proved. The Castillian version of the Reconquista was primarily land based, and was focused on annexing the remaining Islamic areas of the Iberian peninsula. After the Castillian monarchy was merged with the Crown of Aragon, the Reconquista was quickly completed on the mainland. Spain was very much dominated by the Castillian vision of the crusade, despite Ferdinand being from Aragon and the fact that he outlived Queen Isabella. Initially Spain was preoccupied with suppressing local revolts and assimilating its new acquistions. After Charles V's struggle to assume the throne (his succession to all the Spanish possessions was not a given) he became preoccupied with using Spanish resources to pursue his concerns and defend his territories in the rest of Europe.

However, Iberian infighting and European adventures had never permanently hindered the Reconquista in Spain (or it's extension to the Americas) so why did the crusade stall in North Africa? The Pope did in fact approve it and Alexander IV specifically authorized collection of cruzada taxation to pay for the extension of the crusade to North Africa in 1494. The Spanish did indeed make successful attacks in Africa and occupied may of the major ports from 1510-1534. However Castillian style of Reconquista depended on acquisition of land and population to work the land by aristocrats to sustain military efforts when the attention of the crown waned. The African landscape proved unsuitable, since the main economic zone were the port cities and the land was not easily worked by an actively hostile workforce. Perhaps the adventurous gentry who would have tried to make their way in Africa found more rewarding ventures in the American portion of the Spanish empire.

In any case, the expanding Ottoman empire and local Moorish population was able to push the Spanish garrisons out by the middle of the 1500s. Skillful Ottoman naval figures like Barbarossa were able to establish a North African state under very loose Ottoman suzerainty that was able to defeat a major Spanish attack at Algiers in 1541, and counterattack local Spanish successes later in the century. France and Italian states were little interested in contributing to the Spanish control of the Western Mediterranean. Indeed, French and Italian military opposition to Spain was consistent except on the rare occasions the Ottoman empire appeared even more threatening.

Sources:

J.H. Elliot Imperial Spain 1469-1716

Roger Crowley Empires of the Sea: The Siege of Malta, the Battle of Lepanto, and the Contest for the Center of the World