Pallotta admits there remains frustration missing out on the former Bordeaux star.
"Barcelona apologised to us, but I didn't accept their apologies," he reportedly said in a radio interview.
"The only way to accept them is if they decide to give us Messi.
"Barcelona intervened in an unethical way.
"Monchi was in a conference call with [Malcom's] agent and an agreement was made.
"We've now received legal advice and it seems Bordeaux will be called to testify."