Unfortunately MySQL doesn’t have any command to drop all tables or to truncate the database. It has just DROP TABLE and DROP DATABASE.
A solution to drop all the tables without dropping the database could be playing with some pipe, grep and mysql/mysqldump client. Here the result:
$ mysqldump -u[USERNAME] -p[PASSWORD] --add-drop-table --no-data [DATABASE] | grep ^DROP | mysql -u[USERNAME] -p[PASSWORD] [DATABASE]