The protester accused Blair of being on the payroll of JPMorgan Chase when he sent British soldiers in support of American troops during the 2003 invasion of Iraq, The New York Times reported.
"This man should be arrested for war crimes," the unidentified protester shouted before he was subdued by security personnel. "The man is a war criminal."
During his testimony, Blair spoke of his association with media mogul Rupert Murdoch Monday during an inquiry on British media ethics.
"British journalism at its best is the best in the world," Blair testified, explaining that a "close interaction" between media and politicians "has always been the case and is going to go on," the Times reported.
However, Blair said, journalists sometimes blurred the line between news and commentary and were "driven with an aggression and a prejudice."
"It stops being journalism. It becomes an instrument of political power or propaganda," he said, adding it wasn't "confined to the Murdoch media."
"I took the strategic decision to manage this, not confront it," he said of his relationship with British newspaper owners and editors.
Asked whether he had got too close to News International, Blair said he had, but described his association as a working relationship, The Daily Telegraph reported.
"We were dealing with very powerful people who had a big impact on the political system," he said.
Blair hasn't been linked to a core element of the inquiry led by Lord Justice Sir Brian Leveson -- the phone-hacking scandal that enveloped Murdoch's British newspaper subsidiary, News International, since July.
The inquiry has focused on the apparently tight relationship between the Murdoch operation and Culture Minister Jeremy Hunt when Murdoch's News Corp. was trying to gain full ownership of satellite broadcaster BSkyB. The $12 billion bid was abandoned last year as the phone-hacking scandal swamped the Murdoch media empire in Britain.
Hunt will testify Thursday.
Murdoch's top tabloid, The Sun, backed Blair's Labor Party in the 1997 elections. Before the 2010 elections, in which Conservative David Cameron came to power as leader of a coalition government with Liberal Democrats, The Sun backed Cameron's Conservatives.
"There's a view of Rupert Murdoch that he simply backs the winner," Blair said.