No, that feature isn’t directly available on the GitHub web interface (as opposed to the “Revert” button recently added for GitHub for Mac/Windows)
Actually, it is for pull requests only, since June 24th, 2014:
Introducing the Revert Button
you can easily revert a pull request on GitHub by clicking Revert:
You’ll be prompted to create a new pull request with the reverted changes:
git revert is a bit more complex to manage through the web as it can accept a range of commits.
It shouldn’t be an issue in terms of collaboration though: a revert adds a new commit, it doesn’t change the history of existing commits.