Imaging fibers are used to perform real-time fluorescence endomicroscopy, in vivo, in situ, with the goal of increasing diagnostic information for a plethora of organ systems and diseases. Widefield fiber endomicroscopy systems are simple, cost-effective, and come with fast image acquisition times. However, alternative approaches such as scanning systems produce higher contrast images with intrinsic optical sectioning, improving the visibility of histological features, albeit at the expense of simplicity, cost, and acquisition rate. We developed a selective plane illumination microscopy endoscopic fiber platform, consisting of an ultrafast laser fabricated end-cap, integrated with a polymer coherent fiber bundle, and an epifluorescence microscope. Polymer fibers are known to fluoresce when pumped with blue light, enhancing the background and noise in images. Our end-cap design circumvents this challenge. We demonstrate a reduction of out-of-focus features, along with improved contrast of in-focus features, in images of a tissue phantom. Moreover, we demonstrate the utility of our platform for endomicroscopy using a whole, ex vivo human lung model.