Dr Rowan Williams was attempting to prevent a worldwide split
Anglican leaders have issued an ultimatum to the US Church by demanding an end to the appointment of gay clergy and the blessing of same-sex couples.
US bishops have until 30 September to respond to the communique, issued after archbishops met in Tanzania.
The leaders also announced that the US Episcopal Church must allow members who oppose gay clergy to worship under a newly formed pastoral council.
The crisis began when the US Church approved an openly-gay bishop in 2003.
Conservative churchgoers were angered by that decision, as they believe homosexuality is contrary to the Church's teachings.
However, liberal Anglicans have argued that biblical teachings on justice and inclusion should take precedence.
The communique drafted by the archbishops in Tanzania comes after a series of meetings aimed at preventing a worldwide split on the issue.
The document calls for the US House of Bishops to "make an unequivocal common covenant that the bishops will not authorise any Rite of Blessing for same-sex unions".
It also asks for confirmation that "a candidate for Episcopal orders living in a same-sex union shall not receive the necessary consent - unless some new consensus on these matters emerges across the Communion".
It concluded: "If the reassurances requested of the House of Bishops cannot in good conscience be given, the relationship between the Episcopal Church and the Anglican Communion as a whole remains damaged at best.
"And this has consequences for the full participation of the Church in the life of the Communion."
The Archbishop of Canterbury, Dr Rowan Williams, said the document provided "a challenge to both sides".
"A challenge to the Episcopal Church to clarify its position, a challenge also to those who have intervened from elsewhere to see if they can negotiate their way towards an acceptable, equitable, settlement."
He admitted the communique would "certainly fall very short of resolving all the disputes", but said it would "provide a way of moving forward with dignity".
The document announced the setting up of a pastoral council to represent the international church leaders in the US.
Anglicans who do not agree with the Episcopal Church's stance on homosexuality will be able to worship separately to the others, under the auspices of the council.
The body will be made of up five members - three of whom will be appointed by non-US clergy.
Groups such as Integrity, which represents Episcopal gays and lesbians, have accused the leaders of bigotry and urged Episcopalians to lobby their bishops to reject the demands.
Anglican leaders in many parts of the world were angered by the consecration of openly-gay Gene Robinson as Bishop of New Hampshire in 2003.