At the time, O'Reilly said of the Russian president, "He's a killer, though".
He then played a clip of Kremlin spokesperson Dmitry Peskov suggesting O'Reilly apologize for the comment.
"We would like to receive an apology to the president from this respected organization", Peskov told reporters on Monday, referring to Fox News.
During Sunday's pre-taped interview, Trump told O'Reilly that it's better to get along with Russian Federation before the "O'Reilly Factor" host said, "He's a killer though, Putin's a killer".
"I'm working on that apology", O'Reilly said on Monday night.
Late Night host Seth Meyers tore into President Donald Trump Monday night for his comments on Russian Federation. What do you think?
While Trump defends Putin's state-sanctioned murder of political opponents, journalists and people he disagrees with, the question looms as to whether Congress will ever initiate an investigation of Russia's interference in the US elections as their intended result - the installation of Donald Trump as President - succeeded.
The Kremlin reacted angrily to the "unacceptable" interview as it demanded an apology over the comments.
O'REILLY: But he's a killer though.
Trump responded, "He's running his country, and at least he's a leader, unlike what we have in this country".
"The German Chancellor and the Russian President agreed that new efforts must be made to secure a ceasefire and asked foreign ministers and their advisers to remain in close contact", government spokesman Steffen Seibert said. To listen to Trump, Americans should believe a number of dismaying things: our public institutions cannot be trusted; he alone can fix our problems; absent him, our best days are behind us; and, most worrisome, America's ideals have been part of the problem, not the solution. "I have no idea", he said in response to a question. What do you think?
Despite the Kremlin's supposed outrage by O'Reilly's allegations, U.S. President Trump has appeared unperturbed by the remarks.
An open admirer of the Russian leader, Mr. Trump has taken a conciliatory approach toward Mr. Putin, whose tenure has been known for human rights abuses, the brutal suppression of political dissent and the unnatural deaths of many political opponents.
California Democrat and Representative Adam Schiff, who serves on the House Intelligence Committee, called Trump's claim false. "We have the same attitude towards both domestic - federal and regional - and worldwide media", he said.