Commenting on Swedish TV, Stromberg said: "Nobody knows anything. I've talked a bit with some old United players, nobody knows anything.
"It sounds a little strange. If it is about Zlatan wanting to rest a little after a long injury, then nothing is strange. That United's Press Officer does not know anything - feels a bit like that."
Ibrahimovic had played in the previous four games after his comeback last month against Newcastle United - having recovered from April knee surgery.