Washington (AFP) - Donald Trump on Wednesday called on the media to stop their "endless hostility" and "false attacks" in comments addressing a number of pipe bombs sent earlier in the day to Barack Obama, top Democrats and CNN.

Speaking to supporters at a campaign rally in Mosinee, Wisconsin, the US president began with measured remarks arguing public figures had a duty to tone down their rhetoric -- after the top opposition Democrats in Congress accused him of condoning violence and dividing Americans.

"No one should carelessly compare political opponents to historical villains, which is done, it's done all the time," Trump said.

"We should not mob people in public spaces or destroy public property. There is one way to settle our disagreements. It's called peacefully at the ballot box.

"As part of a larger national effort to bridge our divides and bring people together, the media also has a responsibility to set a civil tone and stop the endless hostility and constant negative and often times false attacks and stories," he added. "Have to do it. They've got to stop."

CNN is known for its robust coverage of the Trump administration and for constantly provoking the ire of the president. Signs at his rallies condemn the network.

"There is a total and complete lack of understanding at the White House about the seriousness of their continued attacks on the media," said CNN president Jeff Zucker earlier.

"Words matter. Thus far, they have shown no comprehension of that."

Last week an association representing White House correspondents accused Trump of "cheerleading" violence against the media after the president applauded an assault by a congressman on a reporter.