You could try Hierarchies, making the ped tracks a high number so it's less likely to use
Hierarchy is not a way to restrict travel on some edges. The hierarchical algorithm may not favor the higher level hierarchy roads if the stops are close by.
Correct way is to have a restriction on edges that can be turned on or off for a particular mode of travel. Please see the tutorial data for Paris that sets up different modes and travel costs and restrictions for pedestrians.