No, if you charge rent but aren’t actually investing meaningful capital in the property (most apartment building landlords do not in my experience), then that meets the definition of rent seeking.
From Wikipedia:
> Rent seeking, according to the Georgist, does not include those persons who have invested substantial capital improvements in a piece of land, but rather those who perform their role as mere titleholders.
"Rent seeking" is more about making money by changing the rules instead of providing a service.