Metamaterials with functional responses can exhibit varying properties under different conditions (e.g., waveābased responses or deformationāinduced property variation). This work addresses rapid inverse design of such metamaterials to meet target qualitative functional behaviors, a challenge due to its intractability and nonunique solutions. Unlike dataāintensive and noninterpretable deepālearningābased methods, this work proposes the randomāforestābased interpretable generative inverse design (RIGID), a singleāshot inverse design method for fast generation of metamaterials with onādemand functional behaviors. RIGID leverages the interpretability of a random forestābased ādesignāāāresponseā forward model, eliminating the need for a more complex āresponseāāādesignā inverse model. Based on the likelihood of target satisfaction derived from the trained random forest, one can sample a desired number of design solutions using Markov chain Monte Carlo methods. RIGID is validated on acoustic and optical metamaterial design problems, each with fewer than 250 training samples. Compared to the genetic algorithmābased design generation approach, RIGID generates satisfactory solutions that cover a broader range of the design space, allowing for better consideration of additional figures of merit beyond target satisfaction. This work offers a new perspective on solving onādemand inverse design problems, showcasing the potential for incorporating interpretable machine learning into generative design under small data constraints.