"I feel a deep sense of grief, humility and profound shame having visited the site of the horrific #JallianwalaBagh massacre in Amritsar today. Here, a great number of Sikhs as well as Hindus, Muslims and Christ were shot dead by British troops in 1919," he tweeted.
In his another tweet, he said his first response is to pray to god for healing for those still suffering grief, loss and anger. "And prayer means I must also commit to actions that bridge divides of culture and religion that together we can root out hatred and seek the common good."
Accompanied by wife Caroline, the Archbishop reached the city also known for the Harmandir Sahib, the holiest of Sikh shrines popularly known as Golden Temple, on Monday in his last leg of a 10-day tour.
In a message for the book of condolences at the memorial, the Archbishop wrote: "It is deeply humbling and provokes feelings of profound shame for me as British Christian to visit this place that witnessed such an atrocity over a hundred years ago."
The Jallianwala Bagh massacre is testimony to the brutal killings of innocent and reminds the younger generation of the supreme sacrifices made during India's freedom movement.
In a Facebook post, the Archbishop wrote: "I feel a deep sense of grief having visited the site of the horrific Jallianwala Bagh massacre today in Amritsar, where a great number of Sikhs, as well as Hindus, Muslims and Christ, were shot dead by British troops in 1919.
"I have no status to apologise on behalf of the UK, its government or its history. But I am personally very sorry for this terrible atrocity.
"Coming here arouses a sense of profound shame at what happened in this place. It is one of a number of deep stains on British history. The pain and grief that has transcended the generations since must never be dismissed or denied."
Learning of what happened, the Archbishop said, "I recognise the sins of my British colonial history, the ideology that too often subjugated and dehumanised other races and cultures. Jesus Christ calls us to turn away from sin and to turn to Him as Lord,"
At his visit to the Jallianwala Bagh on February 20, 2013, British Prime Minister David Cameron described the massacre as "a deeply shameful event in British history".
"This was a deeply shameful act in British history. One that Winston Churchill rightly described at that time as monstrous. We must never forget what happened here and we must ensure that the UK stands up for the right of peaceful protests," Cameron wrote in the visitors' book of the memorial.
( With inputs from IANS )