Yes, but with caution. The lens manual states that manual focusing is possible even when the lens switch is set to A. In practice, this is intended as a small manual fine-tune after autofocus, typically with the camera in AF-S mode, rather than full-time manual focusing across the whole range.

The confusion comes from Nikon’s naming: A/M and M/A are different terms on some lenses, and the 18-105mm does not have the same dedicated full-time manual-override setup found on other models. Based on the answers, occasional manual adjustment in A mode is supported by the manual, but it’s not something you should rely on constantly.

Best practice: if you want to focus manually, switch the lens to M. If you only need a slight touch-up after autofocus, turning the ring in A mode is generally acceptable as described in the manual.