"He didn't believe in dumbing down," Mr. Obama said. "He trusted us."
The president said he did not know Cronkite personally, though, like millions of Americans, he was nonetheless touched by him.
"I have benefitted as a citizen from his dogged pursuit of the truth, his passionate defense of objective reporting, and his view that journalism is more than a profession – it is a public good vital to our democracy," he said.
Cronkite, Mr. Obama said, always verified the facts before reporting – something that cost him his job early in his career. Though Cronkite wanted to get the news first, the president said, he would not sacrifice getting it right.
"Walter wasn't afraid to rattle the high and mighty, but never dared compromise his integrity," he said.
Complete coverage of Walter Cronkite from CBSNews.com
Mr. Obama attributed Cronkite's "endless inquisitiveness" to growing up with a mother who sold encyclopedias for a living, and suggested the newsman "never lost the integrity or plain-spoken speaking style" he developed growing up in the heartland.
Other speakers at the memorial service for Cronkite included Katie Couric, Tom Brokaw, Buzz Aldrin, Sean McManus and Leslie Moonves. Also honoring Cronkite was former President Bill Clinton, who called Cronkite "an astonishing man."
"He was always looking for the story, not the storyline," Clinton said. "And there's a big difference."
Watch videos of Walter Cronkite's memorial from CBSNews.com
Obama's Tribute to Cronkite
Schieffer Recalls Cronkite
Katie Couric on Cronkite
President of CBS News on Cronkite
Clinton Pays Tribute to Cronkite
Tom Brokaw Pays Respects
Micky Hart Drums for Cronkite
Dignitaries, Friends Honor Cronkite
Obama Laments Cheapened Discourse Since Cronkite
View photos of Cronkite with newsmakers