In all my Joomla sites, I find too many errors on the Logs/error.log like below:

Joomla FAILURE: Username and password do not match or you do not have an account yet.

I think this indicates someone were trying my admin password. When thinking about the scale of the attempted attack, it feels very uncomfortable.
Shall I do anything about it?
What do you guys do?
And is blocking all the IPs in this list a good idea?