Display Screen or Portion Thereof with Transitional Graphical User Interface

FIG. 1 depicts a first appearance state in a sequence of a display screen or portion thereof with transitional graphical user interface, showing our new design;

FIG. 2 depicts a second appearance state thereof;

FIG. 3 depicts a third appearance state thereof;

FIG. 4 depicts a fourth appearance state thereof;

FIG. 5 depicts a fifth appearance state thereof;

FIG. 6 depicts a sixth appearance state thereof; and,

FIG. 7 depicts a seventh appearance state thereof.