The 34-year-old's current contract runs out next summer, and his future at Stamford Bridge has come under doubt because of the presence of Juan Mata, Ramires, John Obi Mikel and Oscar among others in the team.
"His future is very strong at this club," said Di Matteo. "He's a very important player for us.
"I've had conversations with him, yeah, which I do on a regular basis with the players. I like to exchange opinions. He's very supportive of the team when he's not in the team. When he's in the team, he's a great performer as well.
"From that point of view, we're fortunate to have a very strong squad with international players, so that's going forward with a busy schedule, it's important we use these players."
Lampard joined Chelsea from West Ham United in 2001, and has won the Premier League thrice and the Champions League once with the Blues.