Cardiff boss Dave Jones said: "We've seen it on the video at half-time, it's definitely a penalty.
"To me personally it's a yellow card but the rules state if the striker's facing goal and he gets dragged back then you go off.
"But the referee said he wasn't sure whether he was going to put it in the net. So you figure that one out."
Regarding the match, he added: "I thought we deserved to win it. I thought it was a throwback to the old days when you've got to defend your box from wherever the ball is going to come in from.
"They're a strong side and they play to their strengths, we had to match that.
"It was a good three points for us. But there's a long, long way to go."
Sky Blues boss Aidy Boothroyd was left to rue the penalty decision.
"Early on we showed them far too much respect, we weren't the only ones who were showing them respect but that's for another day and a letter to the referees people," he said.
"It wasn't a penalty at all, it's very, very soft.
"But that's me done, don't ask me any more questions about referees or I'll get myself a fine and I haven't got enough money."
Asked whether he was aggrieved with the overall result, Boothroyd replied: "I was, yes. I thought although it was probably an entertaining game for the neutral, it was a lesson for us really.
"I said the two games - Ipswich and Cardiff - would be a gauge and it tells us that we've come a very long way in a short space of time, but to get to where we want to get to, we're just that little bit off at the moment.
"But the exciting thing is we've got the players and the attitude to do it, now it's just about doing it."
Regarding Bellamy's return to former club Coventry - where he was booed with every touch - nine years after his disappointing sole season in the Midlands, Jones added: "As a player you don't notice it, and I've never known fans to boo a bad player.
"Normally if you're getting booed it means they're frightened of you and maybe that was the case today."