You always have an obligation to give way for pedestrians in a pedestrian crossing, and if visibility is restricted (e.g. if a car in front is obstructing your view of the crossing) a safe overtaking is not possible. For this reason, it is explicitly prohibited in the traffic rules ('Drivers approaching pedestrian crossings must not overtake vehicles or trams which obscure any part of the view of the pedestrian crossing').

Additionally, it is fairly safe to assume that the vehicle you wish to overtake stopped specifically to give way to a pedestrian about to cross the road.

There are no general prohibitions against overtaking trams, on level crossings or in tunnels.