Ok I'm assuming engineering, math, computer science, or related field because it's HN and that your program says GRE is optional for you; if it's required then obviously you have to take it.

These types of programs care most about the quantitative score.

So yes GRE if high quantitative score on timed practice exam, no GRE if low quantitative.

Take GRE practice exam with a stopwatch to estimate your expected score to decide whether to take it.

If you're quite high in verbal and writing but not as good in quantitative I would probably still take it to impress them as an international student, but with a bad quantitative I'd probably say skip it.

I would not worry too much about low verbal/writing if the quantitative is high.