Erling Haaland struck twice to earn the points for the hosts on Saturday.
Afterwards, Tarkowski told evertontv: “We did well in the first half and they had a couple of chances. So did we, but it was quite an even game, and the plan was working.
“And then a simple pass behind us opened us up and if you give a player like Haaland a chance, he's usually going to put it away and that's what he did today.
“You just don't want to give him a chance at goal because he usually scores them, like he did from the cross. Before that, we'd managed them quite well, we shut the space, defended well.
“We always knew we were going to give away chances and we had to rely on ourselves to get a block in or hope Jordan makes a save and we did that. And then the chance was just too easy for him, really.”