The use of fiber-reinforced mortars in structural reinforcement has gained increasing attention due to their ability to enhance mechanical properties while maintaining compatibility with existing masonry structures. In this study, hydraulic lime-based mortars reinforced with basalt fibers treated with Metal-Organic Frameworks (MOFs) were developed and analyzed. The mechanical behavior of the composites was evaluated through three-point bending and uniaxial compression tests. Results show that the incorporation of untreated basalt fibers improved ductility and post-cracking behavior, with an increase in compressive strength relative to plain mortar. MOF-functionalized basalt fibers enhanced flexural performance, achieving an increase in tensile strength and a significant increase in strain capacity compared to unreinforced mortar. However, under compression, MOF-treated fibers led to reduced strength and stiffness, likely due to interfacial discontinuities, whereas untreated fibers provided the best balance of strength and deformability. The comparative analysis confirms that MOF coatings improve interfacial bonding under tensile loading but may compromise compressive performance due to chemical or structural discontinuities. Conversely, untreated basalt fibers enhance both compressive strength and ductility. These findings provide a clearer understanding of the role of fiber surface modification and offer a basis for optimizing reinforcement techniques in sustainable masonry conservation.