The 25-year-old right-back was injured during an aerial challenge with AFC Wimbledon's Steve Seddon on Tuesday night, just five minutes into his league debut for the Tigers.
Despite initially trying to play on, Coyle eventually had to be replaced after half an hour and now faces at least a month on the sidelines.
"Lewie is going to be missing for probably four to six weeks," McCann said.
"We've had the scan results back, it's not as bad as we thought it was gonna be, we thought he was going to need an operation, but it's ligaments right at the top of his shoulder that he has torn.
"We've got to see how it develops over the next four to six weeks. It's not great news for us, or Lewie.
"It was a bit of a poor challenge on him, I would say, coming in from the blind-side and and leading with an elbow and Lewie has landed funny on his shoulder coming down."
Local boy Coyle, a summer arrival from Fleetwood Town, has had to wait patiently for his chance in the Tigers side due to the form of fellow new recruit Josh Emmanuel.
Having fared well during a couple of League Cup encounters, he finally got a chance from the start in League One in midweek, and McCann says that he feels for the player after his night ended in such disappointing fashion.
"It's a big blow. He started the game really well and because of the boy he is, he carried on with it [his injury] for 20 minutes as well," the Tigers chief added.
"He just picked the ball up and threw it down the line and felt it and did the right thing coming off before he made it any worse.
"He had waited time to get his chance. He was really good in the cup games at Leeds and West Ham and even playing with his shoulder like it was, he was playing very well against Wimbledon. It's just very disappointing."
There was however some better news for table-topping City ahead of Saturday's home clash with fellow high-flyers Peterborough United.
Leading marksman Mallik Wilks is back to full-fitness having overcome an illness, while winger James Scott has returned to training much sooner than expected following a second ankle injury sustained at Northampton Town last month.
"Mallik had a bit of a stomach bug on Sunday and Monday so we just didn't risk him. On the Tuesday he felt better so we had him involved and he came on in the game, but he's feeling better," McCann said.
"Of course he will come into consideration - and James Scott is back on the training ground as well - so we've got good quality up there.
"We've got eight very good forwards who could play in this team no problem."
Jordy De Wijs is also in contention for a return at centre-half for this weekend's visit of the Posh.