Smart grid is considered as the next-generation power grid that promises to make power generation and delivery more reliable, efficient, and environment-friendly. This can be achieved using the Advanced Metering Infrastructure (AMI), as it is one of the vital smart grid components. AMI facilitates demand/response management by collecting data from smart meters across the entire grid. However, securing this data is crucial for the overall performance of the grid. In this paper, we focus on securing smart meters data stored in the Meter Data Management (MDM) database at the utility control center of the smart grid service provider. We propose an architecture to secure meter data based on the well-known Role Based Access Control (RBAC) model. In our architecture, we integrate RBAC with the MDM system to ensure that smart meters' data is protected. Through proper assignment of users, roles, and permissions, meters' data will be accessed only by authorized users.