The Uruguayan has been linked with a move to St Mary's all summer and Guaraldi has said that Ramirez has taken drastic action in a bid to transfer to the Premier League.
"He's very angry, Ramirez has told me that he's threatening not to play any more," Guaraldi told Sky Sport 24.
"I've tried talking to him, to explain the situation, that I can't sell him without guarantees.
"Footballers are often badly advised and in this case his agent has made moves without our knowledge."
Guaraldi values winger Ramirez at €15 million (£11.8m) but Southampton haev so far failed to match the Italian side's valuation.