"Jaro never at any time said he didn't want to start against St. Louis," Walsh said in a statement. "A private conversation between a player and coach should stay private and not be discussed with the media."
Halak was traded from the Blues to the Sabres on Feb. 28 in exchange for Ryan Miller. He was then traded to the Capitals before the March 5 trade deadline.
"I am bewildered that a coach would break that trust especially when those comments the coach publicly attributed to Jaro are not accurate," Walsh continued. "It's the coach who makes the decision on who plays in the games, not the players."
Braden Holby started for the Capitals in their 4-1 victory against the Blues.
Halak refused to comment when asked about the incident, telling reporters from the Washington Post and NHL.com that the situation is still too "fresh."
Halak, 28, is set to become an unrestricted free agent this summer.
According to a source close to the situation, TFP has learned that Halak will not sign an extension with the Capitals and will test the open market this July.