I'm a commercial tenant. My sign was obstructed by a community planted tree. What are my rights?

If there is a remedy available, it is probably in the form of injunctive relief--that is, not necessarily money damages per se, but a court's declaration that the tree's presence is an unfair obstacle placed in the way of your business, and a direction to the offending entity and/or individual(s) to trim or remove it, respectively. Equity allows you to get what is fair, even if there is no remedy at law. Also relevant to this discussion is whether you and your commercial landlord agreed, in your lease, to any provisions relating to obstructions to trade signage. If the landlord controls the property on which the tree was planted, there might be a lease provision that speaks directly to this issue. You or your attorney would need to study the lease provisions and see if there are any remedies available therein. If so, you may want to seek those remedies first, and if no other remedies are available, consider hiring an attorney to seek the injunctive relief I mentioned in the first paragraph. If the land on which the tree was planted belongs to the association you mentioned, you would want to first try to work something out with it, and if necessary, have an attorney send the association a demand letter on your behalf, warning that injunctive relief might be sought if it does not reasonably accommodate your request to leave your business signage unobstructed. This is what I see from just the limited information available in your post. I think this is worth consulting with an attorney about. I hope the matter can be resolved in your favor very shortly.

If the tree is on the property of another with whom you have no contractual relationship, I do not see under what authority you can expect them to remove or even trim the tree. You could check with an attorney, but just because you have a sign up for your business, that does not impose any obligations on anyone else unless you have a contract with them. You might consider moving your sign so that the tree does not block it.