Trump's tweet came after a news conference Thursday ostensibly called to announce new labor secretary pick Alexander Acosta devolved into a tirade against the media. The press, the President said at one point, should be "ashamed of themselves."
Smerconish noted in his response to Trump's remarks that the President "uses every opportunity to bash us."
"On his media criticism, I vehemently disagree -- and not just because I'm here at CNN," he said. "The President is attacking of our best checks on government, especially where Congress shows no interest in playing that role."
Now more than ever, people should be investing in journalism and supporting press outlets, the CNN anchor said.
"We all know that in the Internet age, print advertising is plummeting nationally and newspaper staffs have been eviscerated across the country," he said. "In recent months, even revered institutions like The Wall Street Journal and New York Times have been offering employees buyouts and laying people off."
Smerconish called that a "damaging trend," especially for local media.
"Where there's no investigative journalism, government at a local, state and national level goes unchecked," he said.
There is no replacement for fully staffed newsrooms, he added.
"Sure, there's been an explosion of self-described journalists, bloggers," he said. "But people with laptops sitting in their PJs are no substitute for old-fashioned gumshoe, investigative reporters."
America needs "revelatory journalism that takes time and money," Smerconish continued, citing CNN investigative reporting on links between Trump and Russia.
"This is actually a golden age of journalism, one that makes me proud," he said.