The demand for real-time feedback and miniaturization of sensing elements is a crucial issue in the treating vascular diseases with minimally invasive interventions. Here, Fabry–Perot microcavities fabricated via direct laser writing using a two-photon polymerization technique on fiber tips are proposed, designed, simulated, and experimentally demonstrated as a miniature triaxial force sensor for monitoring real-time interactions between the tip of a guidewire and human blood vessels and tissues during minimally invasive surgeries. The sensor contains four fiber tip-based Fabry–Perot cavities, which can be seamlessly integrated into medical guidewires and achieves three-axis force decoupling through symmetrically arranged flexible structures. The results showed that the proposed sensor achieved a cross-sectional diameter of 890 μm and a high sensitivity of about 85.16 nm/N within a range of 0 to 0.5 N with a resolution of hundreds of micro-Newtons. The proposed triaxial force sensor exhibits high resolution, good biocompatibility, and electromagnetic compatibility, which can be utilized as an efficient monitoring tool integrated into minimally invasive surgical intervention devices for biomedical applications.