Error on views after restore a backup

[Alexander Ceballos]

I am getting backups in the following way:
mysqldump --user=$user --password=$password --skip-lock-tables --single-transaction --quick $database > $copia

The problem occurs after restore a backup and with some views for example:

select * from view_ac LIMIT 10;

Error 1449 (HY000): The user specifed as definer ('root'@'%') does not exist.

To solve the problem I execute the following instructions:
update user set host = '%' where user = 'root' and host='localhost';
flush privileges;

But the problem is that instructions enable the remote connections and that is a problem for the the security of my database server.

I have to tell that I have to restore 20 databases and I have a script that automatizes that task, so that is difficult to fix the problem in manual way.