This article provides a workaround to restrict the timesheets at the project level by modifying the project permissions in Jira.
\uD83D\uDCD8 Instructions
Make sure to have Jira administrator permissions to perform the below steps:
Navigate to the respective project, Project Settings > Permissions. Look for Work On Issue permissions and allow access only to a Single user or Jira administrator. This step will ensure no other user can log time apart from the user who has been granted permission.
Note: Make sure the project permissions are associated with a single permission scheme specific to this project.Verify if the users are able to log time from My Timesheet or from the Jira issue view. The results are shown below
These steps are applicable to Cloud and Datacenter.