Latos says suffered the injury in late June during a game against the Texas Rangers.
"I've been pitching with an abdominal strain since the Texas game," Latos told the Enquirer. "I think it was at the end of June."
The 25-year-old Latos pitched in Arlington against the Rangers on June 30, recording the loss despite striking out nine and allowing only two earned runs in 6 2/3 innings.
Latos told the Enquirer about the injury while discussing recent criticism he received from Reds fans during a game last week against the Pittsburgh Pirates.
"I pitched real well all year and I hear nothing but good things," Latos told the newspaper. "But I pitched against the Pirates and I have a bad start. [With] certain Reds fans, I'm not allowed to have that.
"Let alone, no fan knows that I've been dealing with an injury since the Texas Rangers game -- and I've been pitching with it. So I've been pitching the way I've been pitching, but I've been pitching hurt."
Since his outing against the Rangers, Latos has gone 7-4 with a 3.46 ERA in 14 starts. He struggled last Friday against Pittsburgh, yielding four runs and eight hits in six innings.
Latos insisted during the interview with the Enquirer that he was not discussing the injury in order to appease fans.
"It doesn't really matter to me," he told the paper. "I [couldn't] care less because I'm not trying to win over fans or anything like that."
Reds manager Dusty Baker said he did not know about the injury when asked by the Enquirer.
The Reds clinched their second consecutive postseason berth Monday and entered play Wednesday two games behind the St. Louis Cardinals for the NL Central Division lead.