Display screen or portion thereof with an animated graphical user interface

FIG. 1 is a front view of a first image of a display screen or portion thereof with an animated graphical user interface, showing our new design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a third image thereof;

FIG. 4 is a front view of a fourth image thereof;

FIG. 5 is a front view of a fifth image thereof; and,

FIG. 6 is a front view of a sixth image thereof.

The broken lines illustrating a display screen or portion thereof with an animated graphical user interface represent portions of the display screen or portion thereof with an animated graphical user interface which form no part of the claimed design.

The outermost rectangle illustrates the display screen. The broken line showing of portions of the animated graphical user interface illustrates portions of the animated graphical user interface which forms no part of the claimed design.