He subsequently joined Torino on loan, but Seaman is confident that Hart still has a lot to offer for both club and country.
"I must admit I'm having a little chuckle because when you see what Joe [Hart] is capable of, then you see what's going on there [Manchester City] at the moment, it's a shame," Seaman said.
"The decision was made and that's it. I'm glad that Joe is playing at a high quality and then when he comes back with England he still performs like we know he can do."
Seaman is also backing Hart to keep his place in Gareth Southgate's starting XI in the upcoming matches against Germany and Lithuania.
"I know Joe's a good goalkeeper," Seaman added.
"I've always rated him highly, not only because of what he does on the pitch but because of how he reacts from mistakes or setbacks, and he's had a few.
"He didn't have the best Euros but he's reacted properly from it. He's still performing and you look at the guys who are replacing him and you're thinking 'they are nowhere near as good'.
"He's winning anyway because he's playing at a high level of football and he's still performing at great levels and then coming back and playing for England and showing what he can do.
"So for me, his levels haven't dropped."