Urban collective spaces serve key settings for social interaction and play an important role in strengthening social capital and improving citizens’ quality of life. This study, with an applied objective and a quantitative–descriptive approach, investigates the effects of physical components the quality of social interactions in contemporary urban collective spaces Tehran. The research was conducted eight selected districts of Tehran. The study is applied in nature and follows descriptive–analytical method. Data were collected using a researcher-made questionnaire based five-point Likert scale. The questionnaire consisted of 32 items across six main dimensions, and its reliability was confirmed using Cronbach’s alpha coefficients ranging from 0.878 to 0.896. The statistical population included 2,695,041 residents of the selected districts, from which sample of 384 respondents was selected through simple random sampling using Cochran’s formula. Data analysis was performed through Structural Equation Modeling (SEM) using SPSS and Smart-PLS software.

The findings indicated that the overall mean of the physical components of urban collective spaces was 3.09 out 5. Among the examined dimensions, economic components obtained highest mean score (3.23), while social components received the lowest mean score (2.95). The quality of social interactions was evaluated as relatively unfavorable with a mean score of 2.98. In particular, the components of “trust in interactions” (2.68) and “depth of relationships” (2.72) received the lowest scores. The structural model results revealed that 64.2% of the variance in social interactions is explained by physical components, with social components accounting for the largest share of influence (34.9%). Overall, the results indicate that the physical components of Tehran’s collective spaces significantly affect the quality of social interactions; however, these spaces have not been particularly successful in strengthening trust and deepening social relationships. Therefore, improving social, physical, and cultural components in urban planning, along with attention to regional differences, is essential.