The Filipino had surgery to his right shoulder two weeks ago after injuring it prior and during the fight with Floyd Mayweather Jr. on May 2.
There have been reports doing the rounds that Pacquiao could be back in action towards the end of the year, but Arum doubts that will be the case.
In a chat with BoxingScene.com, Arum said that Pacquiao is unlikely to be able to train for six months and that being the case, it's almost impossible to expect him back in the ring and fighting in 2015 again.
"We have to see that there is a full recovery from the surgery," Arum told BoxingScene.com.
"I don't think [he will return this year]. I think it's going to take a good six months before he can even think about training again, but I'm not a doctor.
And remember, these are all averages for recuperation. Every individual is different," he added