Rosenthal, 77, became an op-ed columnist for the Times 13 years ago. Previously, he was executive editor for 10 years.
The Washington Post reported Friday that Rosenthal was forced out. Rosenthal told the Post that publisher Arthur Sulzberger Jr. gave him the news, saying only that "it was time. What that means, I don't know. ... I didn't expect it at all."
"I've had a long time here," Rosenthal told the New York Post. "I love The Times. I'm not happy. But I'm not bitter, either."
Asked about the Washington Post report, Times spokeswoman Nancy Nielsen said, "Mr. Rosenthal was 77 and so it was his time to think about new things, as Abe himself put it."
In his column Friday, Rosenthal said, "I have no intention of stopping writing, journalistically or otherwise. And I am buoyed by the knowledge that I will be starting over."
Before serving as executive editor, Rosenthal was the managing editor, associate managing editor, assistant managing editor and metropolitan editor of The Times. He was a foreign correspondent from 1954 to 1963, winning the Pulitzer Prize in 1960 for his reporting from Poland.
"As a reporter, editor and columnist, Abe has been a major force at The New York Times for half a century," said Sulzberger. "In each of these roles he has excelled."
In an editorial Friday, the newspaper said Rosenthal's "passionate devotion to quality journalism made him one of the principal architects of the modern New York Times."
Rosenthal could not be reached for further comment. The newspaper would not provide a home telephone number for him.
Rosenthal joined the Times in 1943 as a stringer from City College of New York and became a full-time reporter the following year. He has written two books and some 100 magazine articles.