Holy Trinity Church is just 300-metres away from the promenade where Tunisian 31-year-old Mohamed Lahouaiej Bouhlel drove a lorry into crowds celebrating Bastille Day, killing 84 people.
Revd Peter Jonathan Edward Jackson told Premier he has changed his sermon to focus on loving ones' enemies and he believes people who do not usually go to church to be among the congregation.
He said: "I wanted to acknowledge that is the Christian ideal but I also want people to have the opportunity to recognise that is very difficult. It is not fair to people to say glibly 'We're told to love our enemy'. I think you need to look at that in more detail.
"You become aware that, when you have got a large crowd of people, that you need to be very, very gentle, clear and reflective.
"It is not only what you say [that is important], it is what people think you have said and what they have heard. You have got to make sure you are communicating something that enables them to move on a bit."
A man and a woman were arrested in Nice on Sunday morning in connection with the lorry attack, an official from the Paris prosecutor's office said.
The body, which oversess national terrorism investigations, also reported that five people detained previously are still in custody.
Authorities are trying to establish whether Mr Bouhlel acted alone in Thursday night's attack.
Despite Islamic State claiming responsibility for the attack, people close to Mr Bouhlel had not noted any signs of radicalisation.
Revd Jackson said it was "extremely touching" to receive "endless" messages of support from churches in the UK and across Europe.
He added: "When you have to absorb so much personally and try to minister to people's grief and disturbance, it's wonderful to know that other people are actually looking out for you, you're not alone in this and that you're being supported; it really is very important."