There is an option to the configuration file which resembles what you're looking for, but it is not clear if it works for the files being uploaded. From man vsftpd.conf:
Code:
deny_file
This option can be used to set a pattern for filenames (and directory
names etc.) which should not be accessible in any way. The affected items
are not hidden, but any attempt to do anything to them (download, change
into directory, affect something within directory etc.) will be denied.
This option is very simple, and should not be used for serious access
control - the filesystem's permissions should be used in preference.
However, this option may be useful in certain virtual user setups. In
particular aware that if a filename is accessible by a variety of names
(perhaps due to symbolic links or hard links), then care must be taken to
deny access to all the names. Access will be denied to items if their
name contains the string given by hide_file, or if they match the regular
expression specified by hide_file. Note that vsftpd's regular expression
matching code is a simple implementation which is a subset of full
regular expression functionality. Because of this, you will need to
carefully and exhaustively test any application of this option. And you
are recommended to use filesystem permissions for any important security
policies due to their greater reliability.
Example: deny_file={*.mp3,*.mov,.private}
Default: (none)
You can give it a try, anyway.