The 51-year-old Portuguese took over as manager of Milan in June, following Stefano Pioli's departure. It is his second stint in Italy after a two-year spell at AS Roma ended in 2021.
The 19-time Italian champions finished in second place last season but were far behind eventual champions Inter Milan, and had a lacklustre run in the Champions League and the domestic cups.
"As coach of Milan, I feel great responsibility, but also great pride," he told Milan TV on Tuesday.
"When you arrive at a club like Milan, there is the responsibility to defend a side with history known all over the world."
Fonseca also emphasised his intention to trust young players: "For me, age is not a factor. If players have the courage and quality to perform, I will field them," he said.
However, the coach knows he will have to win over a passionate fanbase with a positive brand of football.
"We coaches have an obligation to people who love football, which is not just to win, but to have a 'form' that gets them passionate," he said.
"We must create a spectacle and to do that we need courage, for those we work with to have courage and experience football with joy.
"I think it's fundamental we create a strong sense of identity within the team, which allows us to have quality in our play and ambition to win every game," he added.
Milan begin the new Serie A campaign at home against Torino on Aug. 17.
