The 68-year-old said to Dutch newspaper Algemeen Dagblad: “If it is established that the coronavirus has been defeated, you first have to finish the current competition.
“Sports exists to find a winner, not to say after 25 matches we cut things off and Ajax is champion.
“But while the government has also been following the experts for weeks, some football clubs suddenly say that it is not possible – Ajax first.
“Clubs that misuse this corona crisis for their own gain and then make it a public health statement – I’m a man who can’t take that.
“If it is established that the coronavirus has been defeated, you first have to finish the current competition.”
Van Gaal, sacked by United after winning the FA Cup in 2016, managed Ajax between 1991 and 1997, winning three Eridivisie titles and the Champions League in 1995.