However Fr Aidan Troy stressed it was important that people got on with their lives as normal and the terrorists did not disrupt society.
He was speaking on Premier's News Hour after a French soldier shot and seriously injured a man at the Louvre Museum after he tried to attack him whilst shouting "Allahu akbar".
Police union official Yves Lefebvre said the man was carrying two backpacks, and had two machetes, and reacted when soldiers told him he could not enter with his bags.
A soldier opened fire and the man was struck five times, once in the stomach, Paris police chief Michel Cadot said.
Fr Aidan said: "We were hoping and praying that it wouldn't happen but everyone was thinking it's not will it happen, it's when will it happen.
"There's a terrible sense of despondency around. This is another destabilising situation for the population here in Paris."
Interior Ministry spokesman Pierre-Henry Brandet said that a second person also was arrested but it is unclear whether they were linked to the attack.
Mr Brandet said about 1,000 people were inside the actual museum and were held inside in safe areas.
Fr Aidan said police were "in constant contact" with him and other churches.
"I don't think there's paranoia about that, trying to be responsible and yet not giving in and saying we won't open the school or we won't open the parish," he added.
Fr Aidan Troy speaking to Premier's Alex Williams:
