The midfielder is on-loan with the Sardinians from Inter Milan.
Nainggolan said he doesn't want to think about what's next for him personally and is focused on 'finishing the League' with Cagliari.
“I'm not thinking about anything, now I just think about finishing the League and give my all for Cagliari.
“When things go wrong, it's not easy, we work to get answers. We have lost balance and we have to find it again."