Sheffield said he was hoping to test the free-agent market and get another three-year contract, USA Today said in a story on its Web site.
"This will not work, this will not work at all," Sheffield told the newspaper. "I don't want to play first base a year for them. I will not do that."
Sheffield, sidelined from May 29 to Sept. 22 with an injured left wrist that required surgery, hit .298 with six homers and 25 RBIs in 39 games this season. He played first base for the first time in his major league career after he returned in September.
"I don't know what they're [Yankees] going to do," Sheffield said. "Maybe they picked it up just to trade me. If they do that, if I just [go] to a team for one year, there's going to be a problem."
Messages were left by The Associated Press seeking comment from Sheffield's agent, Rufus Williams, and Yankees general manager Brian Cashman.
It's possible the Yankees are positioning themselves to trade Sheffield, as several teams are reportedly interested in a player of his type. The New York Daily News reported Wednesday that at least a half-dozen teams -- the Angels, Orioles, Cubs, Giants, Astros and Rangers -- are in the market for a power-hitting corner outfielder, and that doesn't include the Red Sox and Mets, who could also use the help. The Yankees can now prevent Sheffield from going to such rivals without getting anything in return.
One GM reportedly called Cashman last week about Sheffield. "To be honest," he said, "I was kind of put off, leaving me to believe he's got at least a couple of teams really pushing him hard [for Sheffield]."
The Associated Press contributed to this report.