Both players featured in Saturday's 1-0 home victory over Stoke City in the Premier League, left-back Cole highlighting his importance to the European champions by popping up with the late winner.
"I am very happy to sign a new contract," Brazil centre-back David Luiz told the club's website.
"I want to play for a long time at the top level - which is what playing for Chelsea means. I love everything about the club and especially the fans who have made me very welcome and given me great support."
The 25-year-old moved to Stamford Bridge from Benfica in January 2011.
Former Arsenal defender Cole is in the final year of his contract and his future has been the subject of intense media speculation in recent weeks.
The England left-back ended a 28-month goal drought on Saturday when he was left unmarked six metres out and deftly lifted the ball over keeper Asmir Begovic in the 85th minute to keep Chelsea top of the league with 13 points from five matches.
"The contract is between Ashley and the club," Di Matteo told a news conference. "My recommendation is to make him stay as long as possible.
"I'm sure they will find a solution. Both parties are happy to talk."
Di Matteo left skipper John Terry and vice-captain Frank Lampard out of his starting line-up against Stoke before the two England internationals came on as late substitutes.
The Italian said there was no question of defender Terry and midfielder Lampard having been dropped.
"It's just about utilising the squad," said Di Matteo after his Chelsea side made heavy weather of beating 13th-placed Stoke. "We have a good squad and we just wanted to bring some fresh players in.
"All the guys have played a lot of games already this season and we've got so many more to come, so using the squad is very important for us. You don't want to get to November and be burned out.
"Since I've taken over I've rotated and used the squad. They [Terry and Lampard] are fantastic, two leaders who lead by example," added Di Matteo.
"When they are out they support the team and support me. It's a pleasure for me to have players like that."
Di Matteo brought in Gary Cahill at the back for Terry and also started with Brazilian Oscar, Spaniard Juan Mata and Belgian Eden Hazard as a trio behind lone frontman Fernando Torres for the first time.
"I thought that worked very well today but it will take time for them to know each other better," the manager said. "It certainly needs more work and practice to tactically integrate them into our system.
"I want them to have mobility and rotation. They are very intelligent at finding free space."
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