They are the ones who disbelieved and obstructed you from the Masjid-al-Haram (Sacred Mosque – Ka’bah) and prevented your offerings from reaching their destination. Had there not been believing men and believing women in the city of Makkah, whom you did not know, and their possibility of being trampled under your feet and thus incurred unwitting guilt on their account. Allah would have allowed you to fight, but He held back your hands, so that He may admit to His mercy whom He will. Had the believers stood apart from them, We would certainly have punished the disbelievers among them with painful punishment.
Meaning:-
Obstruct: to block or close up with an obstacle; make difficult to pass:
Trample: tread on and crush.
Unwitting: unintentional, unintended,