China's chipmaker Sanan is most far advanced among a number of Chinese companies having expressed an interest in Osram, in which Siemens still holds a 17.5 percent stake.
Trade unions at Osram on Friday said any new investor must guarantee to protect jobs.
Kaeser, in an interview with German weekly Wirtschaftswoche cited in abstracts ahead of publication, also said that, given the sale of Osram's lamp unit Ledvance in July to a Chinese consortium, he was not surprised about the follow-up interest.
There would be no large-scale sell-out of German companies, as feared in some quarters, he said.