Bundesliga leaders Leverkusen said the operation was to repair cartilage damage for Rolfes, who has only just returned following a three-month injury absence.
"This is a major shock for us," sporting director Rudi Voeller told reporters. "It is especially painful for Simon and we must now give him confidence and support him as much as we can. He must think positively."
Rolfes felt pain in his knee during a brief appearance in Leverkusen's 3-0 win at Hoffenheim on Sunday.
"One should not hurry to rule him out," Bierhoff told reporters. "We should keep our fingers crossed he comes back and plays soon."
"That is out of the question. This was a fundamental decision," Loew told the SID news agency.
"(Rolfes' injury) is a setback for us but we must first wait and see how long he will be out."
