The term "alert" generally does not mean to say something; instead, it refers to being aware of something or paying attention to a situation. It can also mean to notify someone about a particular circumstance or danger. For example, you might receive an alert on your phone about the weather or a security issue, but in that context, it involves communication rather than simply "saying" something.
If you're thinking about a situation where someone might "alert" others, it usually means to inform them or raise awareness about something important.