Mayor-elect Michael R. Bloomberg expressed doubts yesterday about whether the city should agree to help pay for new stadiums for the Yankees and the Mets in the current fiscal climate.

''We'd all like to have stadiums,'' he said. ''The question is, how can we afford it?''

Building stadiums has been a dream of Mayor Rudolph W. Giuliani, an avid baseball fan. Mr. Giuliani said yesterday that he would do as much as possible to put deals together before leaving office at the end of the month, but acknowledged that the final decision would be Mr. Bloomberg's.

''I won't take away his option, long-term, of making the decision,'' Mr. Giuliani said. ''I don't think it would be right.''

In 1993, during his days as a mayor-elect, Mr. Giuliani was outraged when his predecessor, David N. Dinkins, signed off on a plan to build a stadium for his favorite sport, tennis, during the last month of his term. As mayor, Mr. Giuliani has avoided the product of that plan, the Arthur Ashe Stadium at the National Tennis Center in Queens.

Earlier this fall, Mr. Giuliani pushed to forge baseball stadium deals. Then the World Trade Center was attacked and suddenly he had no time for stadium negotiations. Also, the city's weakening fiscal outlook made a large subsidy for such a structure more difficult to justify.

Mr. Bloomberg said yesterday that he would look at the mayor's proposals for baseball stadiums, but added that he had to study whether taxpayer money should be used to help pay for them.

''I think everybody understands we have to modernize our facilities,'' he said at a news conference, separate from one held by Mr. Giuliani. ''We have to have the best facilities for sports, for entertainment. We have to have housing, we have to have schools, and there are conflicting needs.''

Mr. Bloomberg added: ''I don't yet know the numbers, whether you could justify stadiums at this time. Clearly we're going into very difficult economic times, and we're going to have to make some choices, and it's just too premature for me to give you a definitive answer.''