Marcus Rashford put the Red Devils ahead at the Emirates and after Martin Odegaard levelled it up, it looked like United were heading for all three points when Alejandro Garnacho scored in the 88th minute.
But VAR ruled that the goal was offside before Declan Rice and Gabriel Jesus scored in added time to turn the game on its head and secure the victory.
Some have suggested that Arsenal goalkeeper Ramsdale should have done more to prevent Rashford’s opening goal but Seaman has rubbished those claims.
The ex-Arsenal ‘keeper told his Seaman Says podcast: ‘Aaron got a touch on it, people have asked me if he should have saved it but I don’t think so.
‘He did really well to get a touch on it and he nearly got it onto the post. He was at full stretch and there is no blame there at all.
‘It’s hard. When you have someone like Rashford you know you can’t go early. He can bend it back in from the post, he’s got the other one where he gives you the eyes and puts it down your right.
‘Or what he’s been doing a lot of the time, and Aaron said this after the game, he’s been shooting at the goalkeepers’ legs to try and get it through.
‘You can’t guess with him. I don’t think I would have saved that at all. Aaron was at full stretch and he was unlucky.’
Seaman also took aim at United forward Anthony Martial following the match.
He added: ‘They look dangerous with 10 men, because Martial, oh my god…
‘I swear to you, I was with (my friend) Tom, I said to him to just watch Martial. Watch how he hardly moves. It was a little bit embarrassing.’
United return to action on September 16 when they host Brighton while Arsenal travel to Everton the following day.