How to crop a pointcloud constrained by area above certain mesh?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

I have the following pointcloud:

I also have the topology of the floor represented as a mesh/pointcloud:

My question is:

How i can cut the points of my initial pointcloud, by the mesh figure, leaving everything that is outside of the mesh? (mesh is not ideal plane, it has complex shape) Is it possible with current open3d version?

Thank you in advance!