Pardew left the Saints on Monday, only 48 hours after his side had won 4-0 at Bristol Rovers in League One.
Parkinson told BBC London 94.9: "What's gone on behind the scenes I'm not quite sure - everyone thinks it was a bit of a strange decision."
He added: "But Pardew is a good manager, I'm sure he will be back in the game sooner rather than later."
And Parkinson remains close to his former boss: "I've text him a few times, but I haven't spoken to him yet, I've just left him to it.
"I will speak to him over the next few days though, I think he'll want to get straight back in [to management]."