Berahino has been in impressive form for the Baggies this season, and Irvine is optimistic he can keep hold of the 21-year-old in the January transfer window.
"There's a bit of time to go between now and then, but if he continues to do what he is doing other clubs will come in and test the water," the West Brom boss told reporters.
"That will come down to what the chairman wants to do, but the club is in such a good position we don't need to sell.
"I think the chairman will make the right decision. I wouldn't like to see Saido go, but I have to be realistic as I know what the possibility is.
"Our chairman is very strong and will only do what is in the best interests of the club, and we will have to see whether it comes to that. If things change for Saido and he's done a good job for West Brom, we'll be happy."
Berahino has scored four goals in his previous three Premier League games.