His remarks concluded a week in which the former mayor carved an independent path on a series of issues. Days ago, he blasted a push to legalize recreational marijuana, calling the move “perhaps the stupidest thing anybody has ever done.” On Monday, in an appearance in Washington for Martin Luther King’s Birthday, he did not mention his stance on policing tactics even as another speaker at the event, former Vice President Joseph R. Biden Jr., expressed regret for past support of tough 1990s crime legislation.

Mr. Bloomberg continued that streak on Friday, doubling down on a defense of big business.

“I know it’s very popular among lots of people to say, ‘Oh I don’t like capitalism, I don’t like business,’” he said. “But we all need jobs, we all need an economic base.”

Mr. Bloomberg again declined to answer whether he would run for president in 2020, telling the audience in a brief question-and-answer session that he was still weighing whether he could best help people from the private sector or the White House.

But he also leaned into a pointed rebuke of the president, questioning Mr. Trump’s self-proclaimed expertise as a businessman and dealmaker. He noted that the president inherited the family business and struck deals that “left his customers and contractors holding the bag.”

“To Donald, the art of the deal is simply cheating people and not caring how badly they get hurt, and now he’s doing it to the American people,” Mr. Bloomberg said.