Mr McManus, 26, was gunned down at close range by a masked gunman, who carried out the attack in west Belfast on Saturday night.
The father-of-one was shot twice in the back, as three others - including his 16-year-old brother - looked on.
Speaking at Holy Trinity Church in Turf Lodge, the area where Mr McManus lived for most of his life, Father Brendan Smyth described it as a "brutal and horrific death".
Fr Smyth said the family will "bear the consequences of Kieran's death for a long time to come".
"They have had to deal with their grief in a very public way, and I can only plea that they will be left alone to grieve in the days and months to come once his burial has taken place.
"Sally, you and your family have been dealt a most heinous blow, a blow that has cut to the very centre of your heart, and to the hearts of all your family, and in the days since Kieran's death, you have carried yourself with great dignity in what has been a very speculated about event."
All I can say and plead is for Kieran's death to be the end, the line drawn under these sad days.
Fr Smyth told mourners that, although emotions have been running high since Kieran's death, the desire for retribution and revenge should not be acted upon.
"For nothing will bring Kieran back, nor should, by what we may say or what we may do may only add to the heaviness of heart, or add to the burden that has been forced upon the shoulders of Kieran's family," he said.
"Revenge or retribution is a nasty word and a road that will lead to added heartache."
Detectives investigating the shooting are working to establish a motive for the attack.
They confirmed Mr McManus was known to them.
Speaking the day after his murder, DCI Karen Baxter said the attack was not thought to be sectarian.
On Thursday Fr Smyth told mourners: "We must allow due process takes its course, and that justice be done and those responsible held accountable for their deeds."
The priest asked the community to support Kieran's family - including his mother, brothers, and young son.