Since tourist behavior plays the primary role in protecting the environment, this study has been conducted to extend the psychological perspectives of visitors' environmentally responsible behavior (ERB) in one of the most important natural heritage sites in Iran (Damavand Mountain) in the COVID-19 pandemic timeline and provide awareness for destination environmentalists as well as managers on how to control visitors' behavior. Likewise, Robbins (2002) Organizational Behavior model has been tested on ERB in ecotourism. Generally, 260 reliable questionnaires have been analyzed by using PLS-SEM2.0. The findings showed that (1) Visitors' attitude and ability toward nature would positively affect their ERB; (2) Motivation and learning mediate the impact of visitors' attitude and ability on their ERB; (3) Ability plays a significant role in the formation of visitors' ERB. Thus, the best way to change visitors' behavior is to educate them to make ERB more like a habit.