The Colombia international is being heavily tipped to move to the Premier League this month, with the Nerazzurri reportedly keen to cash in on a saleable asset who has been in and out of Walter Mazzarri's starting line-up so far this season.
However, Alvarez firmly believes that it would be a mistake for Inter to allow Guarin to move to England.
"It's normal that I would not like [him to leave]," the Argentine told Sky Sport24. "For us, he is an important player, who has done very well.
"To lose a player like him would disappoint us, but we still don't know anything. He is still with us and we must take advantage of his presence to the maximum."
Alvarez, who has turned his Inter career around after a tough start to life in Serie A, added he has no intention of leaving San Siro himself.
"I'm happy here and I want to stay," he declared. "There are obvious certain things that I do not know about, but given that up until now they have not said anything to me [about being sold to raise funds], I will gladly remain here."
Indeed, Alvarez admitted that he is hoping to play as much football as possible between now and the end of the season in order to boost his hopes of travelling to Brazil for the World Cup.
"It's an important year," he mused. "First, I'm focusing on doing well here at Inter, one of the biggest clubs in the world.
"Then, as everyone knows, there's the World Cup, a beautiful opportunity.
"But I must do well here. I have to train at my maximum and then maybe the national team will come by itself."