DECLARE @tabName NVARCHAR(128)

CREATE TABLE #res (name NVARCHAR(128), [rows] NVARCHAR(100), reserved NVARCHAR(100), data NVARCHAR(100), index_size NVARCHAR(100), unused NVARCHAR(100))
DECLARE crsr CURSOR FOR SELECT TABLE_SCHEMA + '.' + TABLE_NAME FROM INFORMATION_SCHEMA.Tables
OPEN crsr

FETCH NEXT FROM crsr INTO @tabName
WHILE @@FETCH_STATUS = 0
BEGIN
INSERT #res EXEC sp_spaceused @tabName
FETCH NEXT FROM crsr INTO @tabName
END

CLOSE crsr
DEALLOCATE crsr
SELECT * FROM #res
DROP TABLE #res