The Latics extended their winless run in the Championship to three matches on Monday night as they were beaten 2-1 at the DW Stadium.
Ipswich manager Mick McCarthy claimed after the game that his team were worthy victors, but Rosler believes that Wigan deserved to come away with at least a point.
"The defeat was hard to swallow," the German told the club's official website. "I disagree with what Mick McCarthy said, that Ipswich dominated the game and that they could have won by more goals.
"I have to compliment them though, they roughened us up and bullied us at times in the first half. We had a decent start, but we couldn't get any momentum up because we couldn't stay on the ball."
Wigan are back in action on Saturday with a trip to Bournemouth in the Championship.