The pattern rules for glob are not regular expressions. Instead, they follow standard Unix path expansion rules. There are only a few special characters: two different wild-cards, and character ranges are supported [from pymotw: glob – Filename pattern matching].
So you can exclude some files with patterns.
For example to exclude manifests files (files starting with _) with glob, you can use:
files = glob.glob('files_path/[!_]*')