He made his comments in response to a question from Russian state media reporters at the end of his visit to China in the city of Harbin.
Ukrainian President Volodymyr Zelensky visited the heavily attacked Kharkiv region on Thursday and said the situation had stabilised. The area has come under heavy Russian attack recently.
Putin said the buffer zone around Kharkiv is needed because the Belgorod region, which borders Ukraine, was being massively bombarded with drones and missiles from Kharkiv.
Former Russian president Dmitry Medvedev, who is currently deputy head of the National Security Council, described Zelensky's trip to Kharkiv as a farewell visit.
Russian leaders repeatedly refer to Kharkiv as a Russian city, leading many experts to assume that the Kremlin wants to annex the region. Putin's denial, at least for the time being, is the first time he has stated that there are no current plans to do so.