"Invoke 'P, '" the president tweeted in reference to the company's CEO Mary Barra.
Covid-19 is a respiratory illness.
General Motors issued a statement announcing its agreement to build ventilators with Ventec Life Systems, a small Seattle-area company.
"Today's action will help ensure the quick production of ventilators that will save American lives", he wrote. The automaker said production will begin in the next seven to 14 days with the first shipments of the FDA-cleared ventilators scheduled to begin in April.
All the while, Trump went on Fox News Thursday night to tell Sean Hannity that the need for tens of thousands of ventilators in NY was overblown. "So, it isn't like you can just say 'Close down this assembly line at the Buick plant on Friday and on Monday we're going to make ventilators, or toaster ovens or refrigerators".
The necessary machinery will be delivered to the Warren plant Friday morning and production of masks will begin next week.
In its earlier statement GM said it and Ventec believed they could get production up to a level of 10,000 ventilators per month from their operation, depending on demand.
His harshest criticism was lobbed at GM as he tweeted "As usual with "this" General Motors, things just never seem to work out. You know, you go into major hospitals, sometimes they'll have two ventilators", Trump said.
Toyota Motor Corp 7203.T said it is finalising deals with at least two companies to help increase production of ventilators and respirators.
The "Mary B" reference was to GM's chief executive.
President Donald Trump called on General Motors Corp.to reopen its shuttered Lordstown plant - which GM sold to electric vehicle startup Lordstown Motors Corp. past year - to manufacture respirators needed to fight the COVID-19 pandemic.
Trump has come under fire for his reluctance to utilize the Defense Production Act, which allows the government to direct corporations to produce supplies, like ventilators. Small-government conservatives had urged against such a move, suggesting the threat of the law would be leverage enough.
US President Donald Trump has ordered General Motors to make ventilators for coronavirus patients after attacking the vehicle giant's chief executive.
Tesla Inc TSLA.O said it would reopen its Buffalo, New York, solar panel plant to produce Medtronic ventilators. "Maybe we won't even need the full activation". New York, Michigan, Louisiana and the state of Washington have emerged as virus hot spots in the US.