Michu scored 18 Premier League goals during his first season at the Liberty Stadium after signing from Rayo Vallecano in 2012, but netted just twice in the past campaign.
Ankle and knee injuries restricted the Spaniard to just 17 appearances in the league and there has been speculation that Michu could be on the move in the summer.
However, Swansea boss Monk does not want to lose the 28-year-old and believes that a fit-again Michu will be like a 'new signing' next season.
"He has definitely not been put up for sale by anyone at this club, me, the chairman or anyone," Monk is quoted by Wales Online.
"Our only discussion about Michu is getting him back to fitness and making sure he's on the pitch for Swansea and scoring goals.
"He's a goalscorer, our top scorer two seasons ago, so that's not something you dismiss very lightly. We want him here at the club."
He added in The Sun: "When we were both injured I had a lot of conversations with him and didn't get the impression he wants to leave.
"He wants to do well for the club and for himself. Having him back would be like a new signing.
"There will be interest in him and we will deal with that.
"It would be great if he rests his ankle and comes back strong, meaning we have a really good player on our hands."