"I've never seen more irresponsible personal attacks, mean-spirited slander, and flat-out dishonest attack ads, and I don't expect that tone to change before the election," Warren told the Orange County Register.
Warren was aiming to host the forum this week at his Saddleback Church in southern California, though a date was never formally set.
officials say the campaign had not accepted the invitation nor put it on
any schedule. At the time the
proposed Warren forum was first publicized, the Romney camp said it
was not planning to attend.
Both the 2012 campaigns have made inflammatory charges about each other in recent weeks.
An Obama campaign aide recently said Mitt Romney was either a liar or a felon when describing Romney's personal finances and involvement with his former company. The Romney camp also implored the Obama campaign to repudiate a super PAC ad that linked Romney to the death of a steelworker's wife. Obama has since distanced himself from the ad.
The Romney campaign has also released a barrage of blistering attacks against the president primarily on welfare reform and Medicare. The Obama team maintains those claims are false.
The church event would have had the candidates talking with Warren for almost an hour each, though they wouldn't have been on the stage together. It's the same format that was used in 2008.
Warren earlier said the success of that forum led him to put together a similar event this year.
Fox News' Carl Cameron contributed to this report.