Loew is set to name his 23-man squad for Euro 2012 at the start of May and will decide his first-choice line-up after training camps in Sardinia and the south of France.
"The decision who will play at the Euro will come after two or three weeks of preparations," Loew told daily newspaper Bild with Germany to face Portugal, Holland and Denmark in Group B at Euro 2012, which starts on June 8.
"And if I notice that a player is not in form after a long injury lay-off, then it could well be that I will decide to use a different player.
"Because then it is not about what a player has done for the team, it is about how good he will be at Euro 2012.
"And, of course, I can't decide that right now."
Goetze, 19, made his first appearance of 2012 on Saturday, following a groin problem, after he came off the bench as Borussia Dortmund won 2-0 at home to Moenchengladbach to be confirmed as this season's German league champions.
Likewise, Germany's vice-captain Schweinsteiger, 27, is working his way back to fitness after tearing ankle ligaments in February.
Arsenal defender Per Mertesacker, 27, is recovering from surgery after also tearing ankle ligaments in February which has ruled him out for the rest of the Premier League season.
And veteran striker Klose, 33, has been sidelined with a thigh injury since last month, but it is hoped he will be able to play again for Italian club Lazio this season.
With 114 appearances for Germany, Klose is just five goals short of Gerd Mueller's record as his country's top scorer.
Loew has an embarrassment of riches in midfield with an abundance of talented young players to choose from including Moenchengladbach's Marco Reus and Bayer Leverkusen's Andre Schuerrle.
Franz Beckenbauer, who has both coached and captained Germany to the World Cup title, says Loew will be able to choose from a dream squad.
"We always had a high level of quality in the national team squad, but Jogi, you now have the best squad of all time," Beckenbauer told Bild.
"You have 23 players at a top level, that has never happened before."
Germany will be based in Gdansk, Poland for Euro 2012.
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