Harrington served as a vice-captain in the 2014 and 2016 tournaments and is thought to be among the early contenders to take the main job in two years' time.
However, the three-time Major winner is keen to play at the tournament and hopes that the captaincy opportunity will come up again at a later date.
"[With] the Ryder Cup, Paul McGinley kind of changed the parameters. It took three-and-a-half years out of Paul McGinley's life. It certainly took two years out of Darren Clarke's playing career. I want to be a player. If I go for the captaincy nobody is going to give me back the 45th and 46th years in terms of my playing career," he told Sky Sports News.
"It's a huge sacrifice and as much as I would love to be Ryder Cup captain, selfishly I want to be a golfer. I want to compete and win tournaments so I'm going to push it down the road.
"Hopefully I will get an opportunity down the road. At the moment I am focused on playing. 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."
Europe will be looking to regain the trophy in Paris following their 17-11 defeat at Hazeltine earlier this month.