The Estonia international moved on Friday for £2m,
“I had offers from several teams, including in other countries, but Cagliari really wanted me," the centre-back told Sky Sport Italia.
Klavan will bring valuable experience to the Sardinians, along with Shakhtar Donetsk and Croatia veteran Srna.
“I'm certain we'll do great things here and I am really fired up. The city is wonderful and so are the fans, I can't wait to get started."