The midfielder scored twice in his side's 8-0 win over Santos on Friday and his coach has pleaded with him to remain at Camp Nou
The 26-year-old has attracted intense and public transfer interest from the Red Devils, who are believed to have fielded a final 40 million euro offer for the midfielder.
Having watched Fabregas score twice from the bench in Barca's 8-0 drubbing of Santos on Friday, Martino admitted he wants the ex-Arsenal captain to stay at Camp Nou but says the Spain international will have the final say.
"I'm not thinking about Barca without Cesc," he told reporters. "I've talked to him, I've explained my ideas. He's one of the best in the squad, but there's also a part that he has to decide.
"If it depends on me, he'll stay, and I believe he will, so I haven't thought about who I'd sign to replace him yet."
Martino had announced to Camp Nou from the pitch before the match that he was hoping to help the side to numerous successes this season having taken over from Tito Vilanova in July.
"I just wanted to say that it is with enormous happiness that I am here with the team," the Argentine added. "I want to pass on my pride of being a part of this club and I hope this year will see championship-level achievements for the club."
Fabregas avoided talk of speculation when writing on his Twitter after the match, but shared his delight at the dominating victory over Neymar's former club.
He wrote: "I'm pleased with this good start and to win the [preseason] Gamper trophy is always special for us!"