Fernando Torres scored his first Barclays Premier League goal for six months to put the icing on a sixth win in eight games under Di Matteo.
Di Matteo said: "I thought we were strong, dominated and controlled the game apart from the five minutes when Villa scored two goals."
He added: "Apart from that we had many chances and it was a shame we could not kill off the game earlier, but it was another fantastic performance."
However, Ivanovic's second goal of the game and then Torres' injury-time finish closed the gap on fourth-placed Tottenham to two points.
Di Matteo said: "All the remaining games are massively important and we have done all we could do to put pressure on the sides above us in the Premier League."
Torres had last scored in the league on September 24 against Swansea - he was also sent off - and Di Matteo added: "I have always said it doesn't matter who scores.
"Fernando has been providing goals for others and now he has scored as well. It was a tremendous goal."
Di Matteo will check on the fitness of defender David Luiz (ankle ligaments) and striker Didier Drogba - who was ruled out at Villa Park with a foot injury - ahead of the Champions League game with Benfica on Wednesday.