Tusquets said selling the forward was “desirable” because of the money the Spanish giants could have made.
“I don’t care what’s said outside the club. However, comments from inside the club don’t help us have the calmness we need to do our job,” said Koeman.
“We can’t control what’s said outside, but from within it’s a different story.”
Lionel Messi, who has been at Barcelona his whole career, told the club he wanted to leave in August and said a clause in his deal meant he could do so for free.
Barca said that was not the case and would not let their captain and all-time leading goalscorer go for less than his 700m euros (£624m) release clause.
“If there’s anyone who needs to decide about his future, it’s Leo himself,” added Koeman.
“It [selling Messi] might have been his [Tusquets’] personal opinion and I respect that, but Leo’s got a year left on his deal and he is the one who needs to decide.”