The four-times world and twice Olympic 10,000m champion was forced to retire from Sunday's race after 35 kms, suffering from exercise-induced asthma.
The seasonal condition has prevented him from running London's annual springtime road race since 2007, but the 38-year-old Ethiopian is not expecting it to flare up at next year's showpiece event later in the season.
"It shouldn't have happened in Berlin," Gebrselassie told Reuters in an interview in London's Hyde Park.
"Previously it was true that I could not run the London Marathon because of the pollen but I don't understand what happened on Sunday.
"It is nice here in London in July and August. I have been here on many an occasions for Grands Prix and at that time of the year it is perfect. I am not worried about that."
The men's marathon at the London Olympics is scheduled for August 12.
Gebrselassie, whose four-year reign as marathon world record holder was ended by Kenyan Patrick Makau in Berlin, still needs to set a fast time in order to secure his place in the Ethiopian team for London 2012.
After suffering disappointment in the German capital, he will turn his attention to trying to secure qualification in January in Dubai, where he has won three times and set a course record of 2:04:53 in 2008, or in Tokyo a month later.
"It is very difficult to be top three as the Ethiopians are getting stronger," he said as he relaxed in a cafe following a sun-drenched morning run on the banks of Hyde Park's Serpentine lake.
"I have to do a proper job and try to do at least two marathons in the next five to six months and we'll see and hope it will be okay.
"Athletes have to be confident and I am thinking like that. Dubai in January has good weather and you can run a good time. So I will run either Dubai or Tokyo, I haven't decided yet."
Gebrselassie will be 39 at the start of the London Games and has now failed to finish his last two marathon attempts after dropping out of the 2010 New York race through injury.
That performance prompted him to announce his retirement but the appeal of ending his career on a golden high in London led him to rescind his decision.
He believes his experience could give him an advantage in London, where, deprived of pacemakers, the challenge is to win a gold medal rather than scorch a mark in the record books.
"In the marathon a crazy athlete can just keep pushing from the beginning, at a championship you don't need a time just to win the race," he said.
"The more you are getting older, you lose a little something. Of course there is another advantage, because of your long experience you can use it."
Gebrselassie first broke the marathon world record in Berlin in 2007 before improving his time a year later when he ran 2:03:59 at the same event.
He was dethroned in spectacular style on Sunday, however, when the 26-year-old Makau shaved 21 seconds of his time.
Despite his advancing years, Gebrselassie is convinced he could yet go faster still and said he had set out to lower the bar himself in Berlin.
"Sure," he said when asked if he could regain his world record crown in the future.
"With serious training and serious discipline. By the way, I was training just for the 2:03:30.
"I talked to the pacemakers (in Berlin) about this pace. Maybe I was a bit too ambitious that day."
Despite the disappointment in Berlin, the Ethiopian, who is dubbed the Emperor in his home country, has put all thoughts of retirement to one side.
"In 2007 when I dropped out from London marathon it looked like the end of my career," he said. "Six months later I broke the world record."