There are several options:

As you told, by disabling the external interrupt and clearing the external interrupt flag in the interrupt service routine and later waiting for high state at /INT pin before activating the external interrupt again,

or by using the edge triggered external interrupt, as Andy mentioned,

or by inserting an /INT pin polling loop in the interrupt service routine and only leaving the interrupt routine, when the /INT input went high, which can result in a dramatic waste of time, of course.

I guess this level triggered external interrupt with the interrupt flag not being cleared when serviced by the interrupt routine shall allow single-step operation for debugging.

Kai