The Association of Tennis Professionals say Murray is obliged to feature in the showpiece competition, which concludes five days before the start of the Davis Cup.
"The ATP World Tour Finals is a mandatory event," Chris Kermode, president of the ATP said. "All players who qualify, unless injured, are required to compete in the event.
"Andy Murray has had a fantastic season and earned his place among the world's top eight players to compete at the season finale. We are aware of the comments made after the Davis Cup tie in Glasgow, however our expectations are that, if fully fit, Andy would compete in this year's tournament.
"Unless we hear otherwise via an official withdrawal, he is still entered to compete."
Murray propelled Britain to a 3-2 semifinal win against Australia at the weekend, with two singles victories and a doubles triumph alongside brother Jamie.
Afterwards, Murray told BBC radio he would need extra time to prepare for the final due to a back issue if, as expected, Belgium chooses to host the final on clay.
Belgium's leading player, David Goffin, thrives on the surface and it is also where Murray has struggled in the past.
"The O2 would obviously be a question mark for me if we were playing on the clay," Murray said. "I need more time on the clay to let my back get used to it."
The World Tour Finals are scheduled for Nov. 15-22, with the Davis Cup running over three days from Nov. 27-29.
Britain has not won the competition since 1936 and has reached its first final for 37 years.
Balancing Davis Cup commitments with the ATP World Tour Finals hindered Roger Federer last year.
He had to withdraw from the World Tour Finals title match against Novak Djokovic with a back injury and was then beaten in straight sets by Gael Monfils in the first singles match in the Davis Cup final the following week, but Switzerland still won the event.