The midfielder has been the subject of a public pursuit from United during the close-season, with the Premier League club looking to fill the gap left by Paul Scholes' retirement.
However, new manager Gerardo Martino and Barca vice-president Josep Maria Bartomeu have insisted the former Arsenal playmaker is not for sale.
And he is now set to take part in his first training session since returning from FIFA Confederations Cup duty with Spain.
He wrote on Twitter: "After successful medical tests this morning, I'm ready and looking forward to the 7pm training with all the guys!"
Fabregas came through Barcelona's youth academy, but was picked up by Arsenal at the age of 16 before going on to make his senior debut in the Premier League.
Following eight seasons under the tutelage of Arsene Wenger, he returned to his boyhood club in 2011 and lifted the Liga title last term.
Neymar is also preparing for his first pre-season training appearance with Barca, having competed in the Confederations Cup - where he helped Brazil to victory over Spain in the final.
