The German Olympic Sports Federation (DOSB) rules had insisted that only players ranked in the top 24 would be selected for the London Games, a move which ruled out Mayer, the world number 29, and his 30th-ranked compatriot.
But after lengthy discussions, Kohlschreiber was last week included on the entry list for the Olympics although he admitted he was still waiting for confirmation.
Mayer, on the other hand, has opted out of taking part, preferring to concentrate on his build-up to the US Open, the season's final Grand Slam event.
"That's my decision. I know it's maybe a tough decision to understand," said Mayer, who reached the Wimbledon last eight for the second time, defeating Richard Gasquet of France, 6-3, 6-1, 3-6, 6-2.
"It's a good chance to make points maybe, but we have a tough schedule. I have to play the German Open in Hamburg on clay. Then directly after the Olympics we have the two Masters Series (in the United States).
"I know my body. I cannot play five weeks in a row. That's why I took this decision."
Kohlschreiber reached his first Grand Slam quarter-final at the 33rd time of asking with a 6-1, 7-6 (7/4), 6-3 defeat of American qualifier Brian Baker.
The 28-year-old believes his place in the Olympics will be confirmed by the German authorities.
"We have high standards and I think tomorrow will be the final decision. It's almost confirmed," he said.
"But I'm not thinking about the Olympic Games right now because it's not any more in my hands. I always said I want to play.
"Obviously I'm also putting more pressure on them because I'm doing pretty well here now."
The last two German men to make the quarter-finals of a Grand Slam were Nicolas Keifer and Michael Stich at the 1997 Wimbledon.
Tommy Haas was the last German man in a Wimbledon quarter-final in 2009.