Adam Glapiński said there was now a "big question mark" over what the bank would decide in January, a day after the Monetary Policy Council (RPP) left rates unchanged.
Just a few months ago, council members were discussing possible rate cuts.
"The mood is clearly hawkish," Glapiński told a news conference on Thursday.
"We are afraid rates will have to be raised."
He stressed that no decision had been made, including whether any increase would be a one-off or the start of a series of rises.
The council kept its benchmark interest rate at 3.75 percent on Wednesday.
It has lowered rates only once this year, by 0.25 percentage points in early March.
Joanna Tyrowicz, a member of RPP, told Polish Radio that the current level of rates was too low, but she declined to predict what position her colleagues would take.
Glapiński said future decisions would depend mainly on global commodity markets and on government measures affecting energy and fuel prices.
He noted that the council was concerned with the impact of such steps on inflation, rather than their cost to the state budget.
A month ago, keeping rates on hold had been an easy decision, he said.
Now the picture was more complicated.
He insisted the bank would not act too late, as its policy was based on forecasts covering the next two years.
But he added that unexpected events, such as new geopolitical conflicts or fresh shocks to commodity prices, could change its plans.
Looking further ahead, Glapiński said increased oil production in Venezuela could eventually push global fuel prices down, although any impact would take several years to materialise.
(ał)
Source: PAP, Polish Radio