With the existence of the Prime Directive, it might make sense that there is a reciprocal civilian verison. But we've never heard of such.
The existence of a civilian "Prime Directive" would depend on how often civilians have the opportunity to interfere with non-Federation cultures.
Starfleet needs a general order regarding non-interference because it's out there on the frontier all the time, and the officers need to know that Starfleet Command would frown on one of them setting themselves up as a tin god on some backwater world of primitives.
Civilians, though...how often do they end up on the frontier? As colonists, sure, they're on the frontier, but then again, they're busy setting up a colony, not flitting about in starships. And presumably they've set up shop on an uninhabited world, so no need to worry about Prime Directive problems for them.
Perhaps there is a similar directive among the Merchant Marines? But wouldn't they spend most of their time shipping cargo between established worlds, and not so much on the frontier? Not much point in selling plasma phase converters to primitives that barely mastered indoor plumbing, is there? Though the Merchant Marine might operate survey ships, which could operate on the frontier, so maybe they're
bound by the Prime Directive?