Officers are questioning a 15-year-old girl after police were called to an address and found the victim nearby with life-threatening injuries.
The younger girl was taken to hospital but died a short time later, North Yorkshire Police said.
Rev Andrew Lindlay told Premier prayer was the only answer to "this darkness".
It would help locals to cope and respond in a practical way, he said.
North Yorkshire Police said: "Police were called shortly after 4.30pm on Monday 9 January to an address in Alness Drive in York.
"Officers attended and, upon visiting a scene nearby, they found a seven-year-old girl with life-threatening injuries.
"A 15-year-old girl has been arrested in connection with the incident. She remains in police custody for questioning."
Witnesses described seeing the victim's mother on her knees crying in the street after arriving at the scene.
"The mother was on her knees in the middle of the road, crying and saying things, it was quite distressing," said one woman.
Rev Lindlay, speaking on Premier's News Hour, said: "The first thing we need to do is reach for the goodness and the hope that God offers.
"There will be a lot of pain here and people need holding in prayer. They need to know the love of Jesus.
"The family, I'm sure will be torn apart by this. If we can come to God in prayer we help ourselves and we help them.
"It will be a shock to most people. It's particularly tragic with such a young person impacted so I'm sure people will be moved to prayer and that's what's required for this family".
Alness Drive is said to be a quiet street lined with red-brick detached homes, lying to the south east of the city centre.
On Tuesday morning, the grass track leading from the quiet cul-de-sac to a playing field was cordoned off.
A white tent could be seen on the playing field beyond the cordon.
A single police van was parked on the driveway of a house neighbouring the track to the field.
Rev Andrew Lindlay speaking to Premier's Antony Bushfield:
