I need to perform some actions (prepare gettext *.mo message files) on my project everytime I run
githooks main page there's a complete list of hooks. If it's not on there, it doesn't exist.
That said, there is a post-merge hook, and all pulls include a merge, though not all merges are pulls. It's run after merges, and can't affect the outcome. It never gets executed if there were conflicts; you'd have to pick that up with the post-commit hook if it really matters, or invoke it manually.