Terry's decision to quit England came as a shock to Round, who has previously worked with the defender in the international set-up.
"I was surprised, like everyone else. I worked with him at England for a couple of years and I found him a terrific captain, whole-hearted and 100% every day, every game," said the Toffees assistant boss.
"I couldn't fault him on any issue when I worked with him personally.
"Obviously he feels it is something he has to do but I can't comment on the reasons why he has done it.
"He will be missed because he's a top player and a top defender."