sorry, i found the solution 5 minutes later here :
http://wiki.zimbra.com/index.php?title=Bulk_Create
Create a file for example : 'commands.zmp' with the lines :
createDomain domain.com
createAccount
andy@domain.com password displayName 'Andy Anderson' givenName Andy sn Anderson
createAccount
betty@domain.com password displayName 'Betty Brown' givenName Betty sn Brown
And then execute via console the command :
zmprov < commands.zmp
Hope this help to others with the same problem.
Regards!