The England international has been left out of the starting line-up in the last three games, but the Italian insists the veteran midfielder remains an integral part of his plans
The 34-year-old was left out for the Blues' last match in the Champions League, a 2-2 draw with Juventus, and has also been on the bench for recent games against QPR and Arsenal.
Di Matteo told the club's official website: "He is a very important player for us. I've had conversations with him, which I do on a regular basis.
"I like to exchange opinions and he is very supportive of the team when he is not in it, and when he is in it he is a great performer.
"We're fortunate to have a very strong squad with very good players. Going forward with a busy schedule it's important we can use these players."
Di Matteo also hinted that Lampard will be given the freedom to roam from box-to-box in the centre of the park, despite the former West Ham man typically lying deep in the Blues' 4-2-3-1 formation.
"He's been playing that role but I don't think I've ever taken [the forward running] away from him or said he's not allowed to," Di Matteo added.
"It's his strength, but in that role sometimes we need to be disciplined and it's important for the balance of the team. He's played magnificently last season and this season too so there are no concerns about him."