The historical green structure of Tehran, as part of the city’s natural and cultural heritage, embodies layers of collective identity, spatial meanings, and ecological systems that have evolved over time. Comprising historical gardens, traditional open spaces, and urban green corridors, this structure has long played a crucial role in maintaining ecological balance and landscape legibility in Tehran. However, the dominance of physical development discourse, land-use changes, and weak institutional coordination have led to a gradual disconnection between environmental values and economic interests in urban management. The present study aims to analyze the dominant discourses affecting Tehran’s historical green structure and to identify strategies for reconstructing a conservation-oriented discourse within the framework of sustainable urban development. The research adopts a qualitative exploratory approach using thematic analysis. Data were collected through semi-structured interviews with 20 experts and managers in the fields of urban landscape, cultural heritage, environment, and urban design, and analyzed using NVivo 12 software. The findings indicate that Tehran’s historical green structure is influenced by five main discourses: the dominance of physical development, the absence of an integrated conservation discourse, the identity-forming capacities of gardens, structural and legal challenges, and the strategies for shaping an alternative discourse. The results suggest that the transition from a physical-development logic to an ecological and social discourse requires intersectoral institutionalization, local participation, the revival of collective narratives, and the redefinition of the spatial values of gardens.