New York Fed President John Williams' assertion that policymakers need to "act quickly" as economic growth slows was drawing from research, not hinting at what may happen at this month's Federal Open Market Committee meeting, a spokesperson for the central bank said.

"This was an academic speech on 20 years of research. It was not about potential policy actions at the upcoming FOMC meeting," a spokesperson for the New York Federal Reserve said in a statement.

In his speech at the annual meeting of the Central Bank Research Association, Williams said Thursday, "It's better to take preventative measures than to wait for disaster to unfold."

His comments came amid Wall Street expectations that the central bank will cut its benchmark interest rate during the July 30-31 meeting.

After Williams' remarks, market expectations for a 50 basis point rate cut leaped to about 59%, according to the CME's Fedwatch tool. Prior to his speech, predictions for a half-point cut had hovered at 20% to 30%.

Later, Fed Vice Chair Richard Clarida said on Fox Business News that cutting interest rates quickly is a good strategy. Market expectations for a half-point cut surged even higher to about 69%.

But after the New York Fed spokesperson clarified Williams comments, expectations for a 50 basis point cut fell to about 50% around 7 p.m. ET Thursday.

The Fed currently pegs the overnight funds rate in a range of 2.25% to 2.5% — above zero, but still well below normal levels that have prevailed during past economic expansions.

— CNBC's Fred Imbert and Patti Domm contributed to this report.