Roe will provide innings out of the bullpen for now, and the team will call up another pitcher to take Cahill's spot in the rotation when it rolls around Friday.
Left-hander Tyler Skaggs, who has been pitching well at Reno, seems to be the leading candidate, but right-hander Charles Brewer is also a possibility.
"Could be, yeah," D-backs manager Kirk Gibson said when asked if Skaggs would get the start. "He would be lined up. I don't think a decision has been made."
Cahill struggled mightily in six June starts, going 0-5 with a 9.85 ERA.
Cahill had been hit on his right hip by a line drive on June 19, but said after his last two starts that the hip was not a factor in his struggles.
"He felt like it was resolved, but we've been trying to figure out what's been going on with his arm angle," Gibson said. "We thought he was favoring it. We talked to him after the game. He felt it before the game and into the game. He's compensating and we're not going to mess with that. We're going to get it resolved."
Roe, 26, had four saves and a 2.00 ERA, holding opponents to a .194 average in nine innings over nine games for the Aces this year.
Roe was signed by the D-backs as Minor League free agent last September.