Simplest way - return if in a directory tree you don't want.

use File::Find;

File::Find::find(
  {
    wanted => sub {
      return unless -f;
      return if ($File::Find::dir =~ /^\/var\/log/);
      my $s = -s _;
      return if $min < $s && @z > 10;
      push @z, [ $File::Find::name, $s ];
      @z = sort { $b->[1] <=> $a->[1] } @z;
      pop @z if @z > 10;
      $min = $z[-1]->[1];
      }
  },
  shift || '.'
);

for (@z) {
  print $_->[0], " ", $_->[1], "\n";
}
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Update: a preprocess subroutine seems to be the canonical way to exclude files or directories. But see this post for a caveat I learned about the hard way.