"Our intention is to meet the requirements. It is just taking time to get there," he told journalists.
The CEO of Qantas' international unit, Alison Webster, said the decision was not influenced by Qantas' partnership with China Eastern Airlines Corp.
"I don't think the relationship makes any difference to how we review our response," Webster said.
She said Qantas only needed extra time to make the change because "we have some complexity to work through".
"This is not just Qantas Airways, this is the Qantas group that has to be adjusted," she said. Due to the technology behind Qantas' websites, "it takes some time for us to get to grips with changes that need to be put into the program", she added.
Foreign Minister Julie Bishop reiterated her concerns about Beijing's request.
"Private companies should be free to conduct their usual business operations free from political pressure of governments," Ms Bishop said in a statement on Tuesday.
"The decision of how Qantas structures its website is a matter for the company."
Air Canada, Lufthansa and British Airways are among the 18 carriers that have already made changes on their websites after China's request.
The Chinese Communist Party is known for targeting international companies over the issue.
In January this year, a Chinese regulator suspended Marriott International's Chinese website and mobile app for a week after it listed four China-claimed territories — Hong Kong, Macau, Taiwan and Tibet — as separate countries.
Delta Airlines also came under fire for listing Taiwan and Tibet as separate countries on its website.
China and Taiwan separated in 1949 after a civil war saw the Nationalists flee to the island.
Despite a shared cultural and linguistic heritage, the two sides have been governed separately ever since, but Chinese president Xi Jinping has recently moved to restrict the island country's international influence.