Rooney incurred the problem in England's 1-1 draw away to Montenegro in their World Cup Group H qualifier, with the setback forcing him to miss Saturday's 1-0 Premier League win at Sunderland.
He also sat out the FA Cup quarter-final replay with Chelsea at Stamford Bridge on Monday but, speaking ahead of that game, Ferguson revealed the striker could return to action for the match with rivals City on 8 April.
"He got a groin injury playing for England. He wasn't 100% and there is no point risking players with groin injuries," said Ferguson.
"It could exacerbate itself and you could be out for weeks. Hopefully he will be ready for next Monday's game."