The Blues now must pick themselves up for Saturday's FA Cup final against Liverpool.
"We've been pushing the players for the last two months and they've responded extremely well," said Di Matteo, who also defended his decision to make six changes, including resting both Juan Mata and Frank Lampard.
"Tonight, we have to give credit to Newcastle. They did well and played a very good game against us.
"They have a player in their team at the moment that, whatever he touches, it goes in.
"But my players have given everything.
"We've been asking them to push and push and push and they've done well.
"We'll regroup and pick them up. We've got a big game, a great final, on Saturday and we'll go again.
"We'll look forward to the FA Cup final. It's a great event and the motivation is going to be there."