Perceived security is recognized as one of the fundamental indicators of urban green space quality, playing a significant role in users’ presence, social interactions, satisfaction, and overall experience within urban parks. Users’ sense of security is influenced not only by social factors but also by the physical characteristics and spatial organization of the environment. This study aims to investigate the impact of spatial enclosure on users’ perceived security in Shadi and Mikhak parks in Tabriz, Iran. The research adopts an applied and descriptive–analytical approach. Data were collected through user questionnaires and field observations and were analyzed using descriptive statistics, Spearman’s correlation coefficient, and analysis of variance (ANOVA). The findings indicate that all examined physical components, including form and space, visual and environmental comfort, spatial dimensions and scale, and spatial organization and permeability, have a significant positive relationship with spatial enclosure and users’ perceived security (Sig < 0.01). Among these components, spatial size demonstrated the strongest correlation with perceived security (r = 0.805), followed by spatial organization and permeability (r = 0.799), visual and environmental comfort (r = 0.730), and form and space (r = 0.653). Furthermore, the results of the ANOVA test revealed significant differences between male and female perceptions of environmental security factors, indicating that women show greater sensitivity toward physical and environmental characteristics affecting perceived security (Sig < 0.05). The findings emphasize the importance of integrated physical design strategies, including enhancing spatial legibility, achieving appropriate spatial scale, maintaining a balance between enclosure and permeability, and improving visual and environmental qualities to strengthen perceived security and enhance the overall quality of urban parks. The results of this study can provide practical guidance for urban planners, landscape architects, and designers of public spaces in creating safer, more user-oriented, and socially responsive urban green environments.