(NAP = Non-Aggression Principle)
The NAP is violated when you initiate or credibly threaten the initiation of force on the life, body, or property of another.
Initiating force and causing harm are not the same thing.
If you go up to somebody and punch them you initiated force and it resulted in causing harm. This violates the NAP. Retaliatory force is appropriate (does it mean you have to hit back? Nope, just that you can justify it).
You defend your self from someone punching you by punching them you did not initiate force but if you landed the punch you caused harm and it’s totally justifiable.
You don’t mow your lawn and your neighbors property value drops you did not intiate any force upon their property but you did cause harm. Since you did not initiate force the NAP would say it’s inappropriate to initiate force to resolve this problem.
Saying that force should not be used to resolve a problem does not mean there is no problem and that there can’t be mechanisms to resolve them, just that it should not involve initiating force.
The point of the NAP isn’t to say what’s good and bad just when is force appropriate and inappropriate beyond that it’s up to you to figure stuff out.