Sterling has enjoyed a breakthrough year at Anfield but a thigh injury curtailed his campaign and ruined his chances of being involved with Stuart Pearce's U21s.
The 18-year-old had hoped to use the upcoming European U21 Championship to impress senior manager Roy Hodgson, and insists he had not wanted a summer off.
"I've never come across anyone like that," he told the Daily Mirror. "For me it's not about trying to get a summer off, it's about trying to prove to club and country that you can play football given any chance. Even if it was a friendly game I would want to play.
"But it's best for my long-term career for me not to go to the Euros this summer. It's disappointing because I would love to have gone and proved to the senior manager that I can play tournament football and he can judge me from there.
"The injury happened in an under-21 game. It was a dead leg and then it started bleeding. It got worse from there. Not being able to play the last part of the season was disappointing.
"Everyone thought the manager was trying to rest me, but it was purely because of my conditioning and fitness. So the manager has taken me out of the team. It's been disappointing, but it's best for my career."
Sterling is confident that Liverpool can push on next season and improve on a seventh-place finish, while he knows that if he can make a contribution it will boost his international prospects.
He added: "I want to hopefully get a regular place at Liverpool, get a good run of games and show the manager what I can do with goals and assists and things like that. It's exciting. I can see Liverpool doing really well next season.
"Since Brendan Rodgers has been at Liverpool, the better the football has been. Results weren't really going our way at the start of the season, but as the team grew you can see what he's brought to the club. I can't speak highly enough of him.
"If I can score more goals, contribute more assists and have a good season then hopefully I can make the squad for the World Cup in Rio next year."