WASHINGTON/SAN FRANCISCO Wed Apr 9, 2014 3:31pm EDT

(Reuters) - Federal Reserve policymakers fretted last month that investors would overreact to published forecasts that suggested a more aggressive cycle of interest rate increases was coming down the pike than they planned.

Minutes of the Fed's March 18-19 policy-setting meeting released on Wednesday shed little new light on what might prompt an eventual policy tightening.

After the meeting, the Fed said in a statement that it would wait a "considerable time" after ending its bond-buying program before finally raising interest rates. But Yellen drew the most attention from financial markets when, in a post-meeting press conference, she defined "considerable time" as "around six months" depending on the economy.

That comment, along with published forecasts that suggested rates could rise more sharply than Fed officials previously thought, sent stocks and bonds tumbling that day.

The published forecasts, known as the "dots" charts, foresaw slightly sharper rate increases than officials predicted in the past, with the federal funds rate rising to 2.25 percent by the end of 2016.

The minutes showed that officials wanted to emphasize that the official policy statement, and not the dots charts, give a better indication of the likely path of rates.

Several of the meeting's participants noted the charts "overstated the shift in the projections," the minutes showed, suggesting the Fed is not as eager to tighten policy as some investors might have thought.

Major U.S. stock indexes rallied after the minutes, with the S&P 500 posting its largest daily gain in three weeks, while the U.S. dollar weakened.

"Yellen mentioned the six-month gap between the end of the asset purchases and the first rate hike, and the forecast projections showed a Fed that actually raised their expectations for when they could hike," said Richard Franulovich, senior currency strategist at Westpac in New York.

"The latest minutes seemed to backtrack on that slightly. So overall, the Fed minutes are a bit more dovish."

The minutes, published with the typical three-week lag, showed officials were unanimous in wanting to ditch the thresholds they had been using to telegraph a policy tightening.

"(A)ll members judged that ... it was appropriate to replace the existing quantitative thresholds at this meeting," the minutes said.

"Almost all members judged that the new language should be qualitative in nature and should indicate that, in determining how long to maintain the current (low) federal funds rate, the Committee would assess progress, both realized and expected, toward its objectives of maximum employment and 2 percent inflation."

A couple of the voting members wanted to commit to keeping rates low if inflation remains persistently below the Fed's 2-percent goal.

The minutes did not mention any discussion on what a "considerable time" might mean, and included little on what specific economic conditions might prompt the Fed to raise its key rate from near zero, where it has been since the depths of the recession in late 2008.

"We weren't expecting a ton of changes and we didn't get them," said Todd Schoenberger, managing partner at Landcolt Capital in New York. "As the economy sputters along, the Fed will continue doing what it needs to do."

(Reporting by Jonathan Spicer and Ann Saphir; Editing by Andrea Ricci)