Protesters outside the American embassy were told to "raise their voices in support of international intervention now", in an open letter written to the Irish people by Bishop Carlos Belo, the East Timor spiritual leader and Nobel laureate.
The protest, on Saturday, was attended by at least 1,000 people, including the Labour Party leader, Mr Ruairi Quinn, the Nobel laureate, Seamus Heaney, and Ms Brid Rosney, former press officer to President Mary Robinson.
Heaney told the protesters: "Everybody has felt the pity and the terror of the tragedy. But I think we have also experienced something more revealing, which is a feeling of being called upon, a feeling of being in some way answerable."
The protest was organised by East Timor Ireland Solidarity Campaign and Trocaire. They have called on the Government to invoke the genocide convention of the United Nations in an effort to stop the violence against the civilian population of East Timor.
"The genocide convention must be invoked so that this bloodbath is named for what it is and the UN is forced to send in peacekeepers immediately, with or without Indonesia's permission," said Mr Justin Kilcullen, director of Trocaire, at the demonstration.
Every minute wasted is a life lost, he added.
Ms Collette Craven, from Rwanda, described how her country was "let down by the United Nations, who left the country in the midst of genocide" in 1994.