The leader of the Catholic Church in Ireland has told mourners at the funeral of Ronan Kerr his murder was "an evil deed, an offence against God".
Constable Kerr, who was 25, was killed in Omagh on Saturday when a bomb exploded under his car.
Cardinal Sean Brady said since the murder people have been saying to the killers: "We do not want this. In God's name stop - and stop now."
Constable Kerr was buried at the Church of St Patrick in Drumduff.
Among the mourners at the funeral in Beragh, County Tyrone, were the Northern Ireland first and deputy first ministers Peter Robinson and Martin McGuinness, Irish Prime Minister Enda Kenny and PSNI Chief Constable Matt Baggott.
The leaders of Ireland's four main churches also attended.
Police officers and members of Constable Kerr's Gaelic Athletic Association club, the Beragh Red Knights, formed a guard of honour and helped carry the coffin.
The GAA's joint involvement with the PSNI in the funeral service was unprecedented and has been described as highly symbolic.
No group has claimed responsibility for the attack but dissident republicans have been blamed.
Addressing mourners at the Church of the Immaculate Conception, Cardinal Brady said people "should not glamorise the dreadful pain and sorrow of the past".
"Parents and grandparents, I beg you, plead with your children and with your grandchildren, not to get involved with violence.
"Never let them be deceived by those who say that Ireland will be united or the union made more secure by war.
"They are wrong. It is an illusion. Violence has nothing, absolutely nothing, to offer except misery and destruction."
In his homily, Father John Skinnader, Mr Kerr's second cousin, said: "Ronan loved life - from an early age when he was in the cot at the bottom of the bed where Cathair (his brother) slept - he would get Caithair to pull him out of the cot in the morning so that both of them could begin a day of high mischief.
"Seeing him sitting behind the wheel of the police car last weekend - I thought to myself - there is the symbol of the new Northern Ireland."
Speaking on BBC Radio Ulster on Wednesday morning, the Irish prime minister strongly condemned the attack.
"To those who think they are doing something for Ireland, this is a warped mentality," Mr Kenny said.
"It is the mentality of the past, a very dark and violent past and it has no part in the future."
Dissident republicans remain opposed to the police and have repeatedly targeted officers in both gun and bomb attacks.
Constable Kerr, who joined the police in May 2010, is the second officer to have been killed since the Royal Ulster Constabulary became the PSNI in 2001.
Constable Stephen Carroll was shot dead in a gun attack in Craigavon in March 2009. His widow was among mourners at Constable Kerr's funeral.
Constable Kerr is survived by his mother, Nuala, a widow, two brothers, Cathair and Aaron and a sister, Dairine.