Tawaf is as sacred as Prayer. Therefore the pilgrim must be in a state of purity. The pilgrim should concern himself with supplicating and purifying his heart and intention while offering Tawaf. In addition, the pilgrim should never let anything interrupt his Tawaf unless if there is a genuine reason for that.
The prominent Muslim scholar Sheikh Salih ibn Fawzan Al-Fawzan states: A pilgrim should perform the rounds of Tawaf in sequence, giving each round its due performance. However, he may interrupt his Tawaf if there is a reason for this, such as performing the obligatory Prayer if its time becomes due during his Tawaf. He can perform the Prayer and then resume the Tawaf. Likewise, there is nothing wrong if he rests between rounds when he feels tired.
But if he interrupts Tawaf for a long interval without excuse, he is to repeat it from the beginning.