The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, have both briefed President Clinton on their concerns over the threat to Sinn Fein's continued participation in the Northern Ireland peace talks.
A White House spokesman told The Irish Times that both calls were made on Thursday night. Mr Ahern "briefed the President on the situation and how he sees it".
The spokesman said: "Both of them were obviously concerned about keeping the peace process on track. They discussed the current situation. Beyond that there was no decision."
The spokesman said the question of Sinn Fein's continued attendance at the peace talks was "a matter for the two governments to decide, consistent with the Mitchell Principles". He said the US has "repeatedly condemned all usage of violence as totally unacceptable and counterproductive, and we continue to do so.
"As far as the peace talks are concerned, we are not a party to the talks and the two governments must decide".