Replays showed Kovacic's second yellow for the challenge on Xhaka was harsh as it was the Arsenal midfielder who looked to be on top of the Croatian international in a 50-50 challenge.
Lampard fumed after the 2-1 defeat at Wembley game: “That is nowhere near [a red card] and it changes the game.
“I cannot fault the lads effort for pushing, but that is never a red card. Again, coming back to us we did not do enough to win the final."
He continued: “What kind of rule is that? There has always been this one about how you couldn't challenge two yellows.
“Someone is sitting there stubbornly sticking to their guns on that one because if we have VAR that is great.
“Let's use it as much as we can to get the right decision."
However, Lampard was also not impressed with his side's performance despite Taylor's decisions going against them.
“I think the main factor being we did not do well enough to win a final in reality and that sums up where we are at," he added.
“People were getting excited that we got top four, which we are happy with because we know it was a big challenge for us.
"But we weren't ourselves and inconsistency has been a problem."