The National Football League accused Dallas Cowboys owner Jerry Jones of trying to sabotage its contract negotiations with commissioner Roger Goodell, calling his conduct “detrimental to the league’s best interests.”

The tension has grown so severe that the topic of removing Mr. Jones has been discussed by at least some owners, according to people familiar with the matter. That type of drastic action would require the league showing conduct detrimental to the league—which is exactly the language the league used in a letter...