Ethan Ampadu seemed to be fouled by Irish goalkeeper Darren Randolph during the goalless draw in the Nations League but the referee decided against it as VAR was not in use - and Giggs has suggested it should be in operation consitently.
Giggs said: "Perhaps we would have got it if there was VAR. You would like consistency all the way through [in the way VAR is utilised].
"You would have liked the referee at least to have gone over and have a look, which I'm always in favour of - the referee being in charge and having a look.
"The goalkeeper drops it, he [Ampadu] heads the ball - that's not a foul by Ethan. We would've liked a penalty but it certainly wasn't a foul by Ethan, so I don't know what the referee was doing."
Wales remain top of their Nations League group after the draw and Giggs was satisfied with the result.
He told the BBC: "I'm happy with the result. I thought the performance wasn't great. We didn't really get into our rhythm. Ireland, credit to them, they made it difficult for us - they pressed us all over the field.
"But I'm delighted with three games and seven points from nine. You have to be happy."