Song, the former Arsenal midfielder who spent six years at the Emirates before moving to Spain in 2012, says his team-mate has no intention of quitting Camp Nou.
Fabregas, also a former Gunner, has been the subject of two bids from Manchester United already this summer, and David Moyes said this week he will give the transfer "every opportunity to materialise".
But after featuring in Barca's friendly defeat at Bayern Munich Song told Sky Sports News he is "100%" sure Fabregas is going nowhere.
He said: "I did not speak with him but I know Cesc is 100 per cent here.
"He loves Barcelona, he loves the club. He will stay here next season and give 100 per cent because I know him very well and he'll want to fight. He's focused on the club.
"He wants just to give his best for Barcelona. He's from Barcelona, he loves Barcelona and he'll want to start the season to show what he can do.
"People are talking and talking, but we know he is focused here and ready to start the season.
"He's enjoying a holiday with his family and I'm sure he wants just to come back here.
"It's my own opinion but I know he will stay here, 100 per cent."