You can use css
disable all
textarea { resize: none; }
only vertical resize
textarea { resize: vertical; }
only horizontal resize
textarea { resize: horizontal; }
disable vertical and horizontal with limit
textarea { resize: horizontal; max-width: 400px; min-width: 200px; }
disable horizontal and vertical with limit
textarea { resize: vertical; max-height: 300px; min-height: 200px; }
I think min-height should be useful for you