At his first media conference since joining Marseille in May, Bielsa revealed his anticipation about coaching at the Stade Velodrome, while he attempted to distance himself from the departures of Valbuena and Diawara - who played a combined 489 games for the club.
Valbuena has joined Dinamo Moscow in Russia, while Diawara signed for Nice.
The departure of Valbuena was of particular disappointment for Marseille's fans with the 29-year-old midfielder having spent eight seasons with the club, and Bielsa underlined he would have preferred if the France international had stayed.
"Valbuena was the best Frenchman at the World Cup," the Argentine coach said.
"I am aware of his career. And besides it's not me who decided his departure. Nor Souleymane Diawara."
Bielsa also rejected the suggestion he does not like dealing with the media, despite the fact it took over three months for the man known as 'El Loco' to complete a news conference.
"My presence here at this press conference proves that I have no problem with the media. I will be here twice a week, as the rules state as established by the league: before and after every match," he said.
"I am not in conflict with the media. The public is informed via the media, so there is no problem.
"Speaking to the media allows me to clear up any misunderstandings and transfer important messages to the public."
Marseille will start their Ligue 1 campaign on Saturday with a trip to Bastia before their first home match on August 17 at Stade Velodrome, which Bielsa claimed is "incredibly exciting".
The 59-year-old former Athletic Bilbao and Chile coach added Marseille's passionate supporters and the southern French city's love of the club had inspired him to take over from Jose Anigo.
"First of all, I joined because of the players at the club and the atmosphere inside the Vélodrome when it's full," Bielsa said.
"Marseille is a city of diversity that advances as one. For me, I like the idea of giving this diversity a common goal.
"It is a great challenge to try and place the club amongst the leaders in Ligue 1.
"My players are 100 per cent professional and I haven't experienced that so many times in my career."
