Marash said he felt that attitude more from British administrators than Arabs at the Qatar-based network.
Marash was the highest-profile American TV personality hired when the English language affiliate to Al-Jazeera was started two years ago in an attempt to compete with CNN and the BBC. He said there was a "reflexive adversarial editorial stance" against Americans at Al-Jazeera English.
"Given the global feelings about the Bush administration, it's not surprising," Marash said.
But he found it "became so stereotypical, so reflexive" that he got angry.
Marash, who's being replaced by former CNN International host Shihab Rattansi, said he was the last American-accented anchor at the network, which broadcasts from Washington, London, Kuala Lumpur and Doha, Qatar. He said there are more Canadians than Americans working at the Washington office.
Will Stebbins, Washington bureau chief for Al-Jazeera English, denied any bias against Americans.
"We certainly evaluate U.S. policy rigorously," he said. "But we do our best to give everyone a fair shout."
Al-Jazeera English has been largely unsuccessful in getting U.S. cable or satellite systems to pick it up, except for the municipal cable system in Burlington, Vt., and a small system visible in Toledo and Sandusky, Ohio. But its programming is available on the network's YouTube site.
Marash said there were other reasons for his exit. He said the network has quickened the pace of its broadcast instead of having the slower, more reflective tone that he had expected. But he praised the network for its coverage of issues south of the equator.
He said he plans to write a book and hopes to teach. His exit was first reported in the British publication The Guardian; Marash's last day was March 21.
Stebbins said Marash was recently told that he would no longer be an anchor at the network. Al-Jazeera thought Marash was better utilized as a reporter, and singled out a recent series he did on American suburbia as worthy of praise.
"We were sorry to see Dave go," he said.