Sabine Kehm also revealed that Schumacher had just gone to the aid of a friend before he sustained serious head injuries while skiing in France.
A statement from Schumacher's family on Monday had asked the press to respect their privacy but this has apparently been ignored.
Kehm, in quotes reported by German newspaper Die Welt, said: "Apparently a journalist dressed as a priest tried to gain access to Michael's room. I wouldn't have ever imagined something like this could happen."
Kehm also revealed details of what had happened according to what she had been told by eyewitnesses.
"Many people who were there have described the situation to me," she said.
"Michael had helped up a fallen friend shortly before and was therefore not going at high speed.
"He then went over a boulder, which he had not seen, and as a result lost control. That he then hit his head against another rock is a great misfortune."
On Tuesday doctors at the University Hospital of Grenoble said Schumacher's condition had improved slightly.
Seven-time Formula One world champion Schumacher remained in a critical condition and was still in intensive care after the accident in the resort of Meribel on Sunday.
However, the medical team were able to perform surgery overnight Monday which released some of the pressure on Schumacher's brain and removed a dangerous haematoma (collection of blood).
Doctors said on Monday that the accident would certainly have killed the 44-year-old German if he had not been wearing a helmet.
The surgeons admitted to being "surprised" at the improvement in Schumacher's condition, with a scan on Monday afternoon giving them the go-ahead to perform a procedure they had not expected to be able to safely execute.
"Late on (Monday) evening a new brain scan was carried out and there was a slight improvement," Jacqueline Hubert, the director general of the hospital, said.
"The scan allowed us to suggest we could have a new intervention (on the brain) and that took place overnight. A new scan was carried out this morning and this shows slight improvement."
It later emerged that the surgery on Schumacher, a winner of 91 grands prix during a stellar career, had taken place at 10pm local time on Monday.
While Schumacher's condition had improved, the doctors admitted they could not yet say that he was out of danger and that the coming hours and days were still crucial.
Doctors also confirmed that Schumacher remains in a medically-induced coma and that there is no way to predict his future condition.
It was also confirmed that Schumacher will remain in Grenoble for the foreseeable future while he continues to be treated.