WASHINGTON  The chairman of the Federal Reserve, Ben S. Bernanke, warned on Monday that high unemployment and a continued reluctance by banks to make loans were likely to slow the economic recovery for the next year.

And in a departure from the usual practice of Fed chairmen, Mr. Bernanke tried to reassure global investors about the recent fall in the value of the dollar by saying that the central bank was “attentive to the implications of changes” and would “continue to monitor these developments closely.”

It is rare for Fed officials to comment on exchange rates, which for decades have been the responsibility of the Treasury Department. Mr. Bernanke’s message seemed to be that the Fed saw no cause for alarm in the dollar’s weakness and that it would not need to bolster the dollar by raising interest rates sooner than it would otherwise.

Taken together, the Fed chairman’s comments highlighted the conflicting goals that Fed officials may have to balance. To nurture the slow recovery and bolster employment, the central bank has vowed to keep interest rates low for “an extended period,” but to prevent a precipitous drop in the value of the dollar, which could stoke inflation, the Fed would have to raise interest rates.