"As long as I am a professional footballer, I will always be available for the national team if I am needed," Muller said.
"When, whether and how, is of course up to the national team manager."
Muller declared after Germany's disappointing group stage exit in Qatar he would take some time to consider his future.
Immediately after Germany were eliminated before the World Cup knockout stage for the second successive time, Muller told sideline cameras "everything I have done, you can be sure I did it with love", giving rise to predictions he would announce his international retirement.
Speaking from Bayern's winter training camp in Qatar, Muller said he was "emotional after the game" and had "thought about and discussed (retirement) with (Germany coach) Hansi Flick".
Muller, who has played 121 competitive games for Germany and was part of the team that won the 2014 World Cup, said he looked forward to helping the side return to the pinnacle of international football.
"We must -- and will -- manage to be successful again.
"It's less about particular players. The coach has many options - there are many young players.
"I'm calm but absolutely ready if the coach needs me."
Muller started up front in each of Germany's three games in Qatar, but was unable to add to his tally of 10 World Cup goals.
The 2010 golden boot winner has not found the back of the net at World Cup level since scoring in Germany's 7-1 demolition of home nation Brazil at the 2014 World Cup.
