Former U.S. Labor Secretary Robert Reich told President-elect Donald Trump to stop attacking people on Twitter because it was petty.

"Let me just say, because Donald Trump is probably watching right now, let me just say: With all due respect, Mr. Trump, you are the president-elect of the United States; you are looking and acting as if you are mean, and petty, thin-skinned, and vindictive," Reich told CNN host Anderson Cooper.

"Stop this. This is not a fireside chat. This is not what FDR did. This isn't lifting people up. This is actually penalizing people for speaking their minds."

Trump has, in the last week, fired off tweets criticizing Boeing, the union president of Carrier – the company he struck a deal with to help keep jobs in the United States – the media, China, Green Party's Jill Stein, and the show "Saturday Night Live."

"What you did with Boeing the other day – minutes after the CEO of Boeing was quoted as saying that you, Mr. Trump . . . were wrong on international trade, what did you do?" Reich said. "You tweeted that Boeing should have an order cancelled, where you called it a $4 billion order."

Trump defended his tweeting on NBC's "Today" earlier Wednesday, saying, "It's a modern-day form of communication. . . . I get it out much faster than a press release, I get it out much more honestly than dealing with dishonest reporters because so many reporters are dishonest."