"My only interest at the moment is to play rugby at the highest level," he told the Irish Examiner.
"The timing of this news wasn't the best but the issue is closed as far as I'm concerned."
O'Gara, who was born in San Diego, was linked with four-year move to Miami that could net him $12million but he insists the reports were exaggerated.
"After an initial approach, I have not been in contact with anyone in America," he said.
"I won't be thinking about it because my only concern now is to help Ireland through the remaining games of the Six Nations. I want to play for Ireland and I want to play for them in the World Cup.
"I haven't given the slightest thought to what might happen later in my life. This thing appears to have snowballed beyond belief."
O'Gara is expected to be named on the bench for Ireland's next match in Cardiff on Saturday.