"I want to be a player," Harrington told Sky Sports. "If I go for the captaincy nobody is going to give me back the 45th and 46th years in terms of my playing career.
"It's a huge sacrifice and as much as I would love to be Ryder Cup captain, selfishly I want to be a golfer."
The Irishman said the commitment to leading the team had taken years away from the playing careers of the last two European captains.
"With the Ryder Cup, Paul McGinley kind of changed the parameters. It took three-and-a-half years out of his life. It certainly took two years out of Darren Clarke's playing career," he added.
"Hopefully I will get an opportunity down the road. Whether it's a reality or not or whether it's a possibility, in my head I am going to make the Ryder Cup team in 2018."
A decision on Europe's next captain, with Denmark's Thomas Bjorn regarded as the favourite, is expected in the coming months
The United States defeated Europe 17-11 in Minnesota earlier this month to get their hands on the Cup for the first time since 2008.
(Reporting by Shravanth Vijayakumar in Bengaluru)
