Javier Hernandez scored the only goal after 11 minutes, bringing an end to Swansea's unbeaten home record.
Ferguson sees room for improvement from his side.
"They have a great home record so we had to make sure we defended well and I think we did that," he said.
"They have a good football team and kick the ball well. We have to concentrate all the time and that concentration was short today.
"We maybe should have done better with the chances we did get on the counter-attack and near the end we could have had a couple of chances, but it was a good result."