He threatened this morning, on the heels of the attack on CNN, that the mass media "had better get its act to together and fast".
"Don't let the terrorists win", he said.
Sen. Orrin Hatch, a Utah Republican, said: "I don't see anything really wrong with the president. Have you ever seen this?"
With the United States bitterly divided and crucial midterm elections on November 6, Trump had first reacted by calling for unity and condemning "acts of political violence", before reverting to attacks on the media.
The package had been received in the general mailroom on Wednesday, according to a law enforcement official. It was compact, perhaps about the length of a wooden spoon, and contained wires and a black pipe, officials said.
The FBI has said that at least five of the packages bore a return address for the Florida office of U.S. representative Debbie Wasserman Schultz, who formerly chaired the Democratic National Committee. "Never, never", Wasserman Schultz said at a campaign event north of Miami on Thursday night. Philip Bartlett, inspector in charge of the U.S. Postal Inspection Service's NY division, said Thursday afternoon that the Postal Service had found nothing since early that morning, leaving the tally at 10 packages.
Rep. Steve Scalise, R-La., who was severely wounded in a 2017 shooting that targeted Republican members of Congress on a suburban baseball field, wrote on Twitter that he had experienced "first-hand the effects of political violence" and said that as a nation "we must agree that this is a unsafe path and it can not become the new normal".
Campaign chairman Brad Parscale later apologized, saying it was a pre-programmed message that was not caught before news of the pipe bomb came out. "Clean up your act.try to act Presidential".
The packages were sent in manila envelopes with bubble wrap, marked with computer-printed address labels.
Mr Holder's package had the wrong address and was sent to Ms Wasserman Shultz's office in Florida after the package could not be delivered to his address.
The devices all were sent to an Federal Bureau of Investigation lab in Virginia to be studied. Officials provided no details on a possible suspect or motive.
The packages had numerous hallmarks of suspicious mail, including large block lettering and excessive postage aimed at making it harder to track, said Matthew Doherty, who formerly led the U.S. Secret Service's National Threat Assessment Center.
The package bears similarities to the ones that have recently been sent to the homes of Bill and Hilary Clinton and billionaire businessman George Soros, as well as the office of Barack Obama. The bombs have been sent across the country - from New York, Delaware and Washington, D.C., to Florida and California, where Waters was targeted.
CNN, citing a law enforcement official, was initially told a suspicious package containing a pipe bomb that was addressed to the White House was intercepted at Joint Base Bolling in Washington, DC.
"Stop blaming others. Look in the mirror".
Even as everyone condemned the unknown sender and Trump decried political violence, blame flew for the corrosive nature of America's political conversation.
Sayoc's previous run-ins with law enforcement date back at least to an arrest for larceny when Sayoc was 29 years old, according to state records.
The device addressed to Clinton in Westchester County, north of New York City, was found late on Tuesday by a Secret Service employee who screens mail for her, the statement said. O'Neill said in an appearance on CNN that he was "pretty sure those images will be caught on video, and we'll be able to find out where that person came from before they entered the building and where they went to after".
It is unclear who the package was addressed to, said cops. Some were discovered in mail processing facilities.
"The full weight of our government is being deployed to conduct this investigation and bring those responsible for these despicable acts to justice; we will spare no resources or expense in this effort", he told a gathering in the East Room of the White House.