How to react to strongly erroneous and irrelevant citation of my article?
Begin by trying to speak to the author and see what he says.  Then:

Speak to the editor of the journal, unless the author is willing to submit a correction instead.  If the problem is big enough that it:

a) Misrepresents your work to the degree that someone would think, from this article's citation alone, that you did or did not do something critical, or

b) Invalidates the results of the paper in which the citation is published, or

c) Undermines those results by providing a false citation to make it look like a claim is better supported than it is

then it is important that the editor be involved and the article be corrected.

If it's a small problem, then speaking to the editor may not do much.  As an example, a paper of mine was cited incorrectly once.  It was actually a small and irrelevant mistake, and the authors probably meant to cite something else.  It was along the lines of: "Other techniques to solve this problem include Y, which was explored in [1][2][3], but we are approaching it differently" and that was it.  In this case, embarrassing the author was not something I felt like doing so I let it go.