The RTE football pundit, who has a reputation for being outspoken and controversial, was damning in his criticism.
The panel, which included Johnny Giles and Liam Brady, were discussing the Dutch manager following United 4-0 victory over Club Brugge when Dunphy called Van Gaal a "spoofer".
Asked by host Darragh Maloney what he meant and Dunphy replied: "he's a total bulls*****."
Maloney then said: "Ah c'mon Eamon, I know we're after the watershed, but you can't say that."
The 70-year-old has a history of making shocking statements on television.
GETTY
Eamon Dunphy is unconvinced by Louis van Gaal
During the World Cup last summer, the Irishman swore live on air before Brazil's clash with Mexico.
Dunphy said: "When Neymar was shaping up to take that penalty, I thought he was f**king dreading it."
The pundit later apologised claiming he thought the programme was on an advertising break.
We use your sign-up to provide content in ways you've consented to and to improve our understanding of you. This may include adverts from us and 3rd parties based on our understanding. You can unsubscribe at any time. Read our Privacy Policy