You can share Imported contacts with users by using Delegate Contacts option, but it will only allow to share upto 25 users.
- In the Admin console or from user, Select Contacts
- Select More option, In drop down list select Import
- Upload .Csv file and Import
- Now select newly Imported contacts tab (appear under My Contacts tab at right side)
- Select all and click Group icon
Under this tab Select My Contacts and Apply
- Select More option
- In drop down Select Manage delegation settings
- Enter Id's you want to share My contacts in Invite People tab
- Select Send
- Now user can see shared contacts under Delegated contacts