The Adria Tour, organised by the world number one, saw Djokovic, Grigor Dimitrov, Borna Coric and Viktor Troicki all test positive for Covid-19 after the Croatian leg of the event.
The fallout saw the organisation of the event, its lack of social distancing and large crowd come in for some severe criticism.
Djokovic told Serbian outlet Sportski žurnal that he felt some of the criticism constituted a witch-hunt - and Thiem has added that he felt the criticism of his rival was unfair.
"It was unfair to him because he didn't break any law and he didn't force us," Thiem told CNN Sport.
He didn't force any player to come there. He didn't force any player to interact with the fans.
"It was our own decision. The whole event was for a very good cause as well."
Novak Djokovic hails 'fantastic news' of US Open going ahead
The event had attracted a host of top players including Thiem and Alexander Zverev but the series – which was due to visit Montenegro and Bosnia and Herzegovina - was cancelled after Djokovic tested positive.
Thiem put the lack of social distancing down to player excitement.
"It was obviously a mistake from everybody but it's a long time ago now really and everybody who got positive there is healthy again, which is a very good sign as well," he said, before adding that everybody had learned from their mistakes.
In reality, we saw happy fans, we saw happy kids and then we kind of forgot to keep the distance, to not take pictures, to not hug the kids and it was a mistake.
"Everybody regrets it, of course, but I think, at the same time, it's fine now."
Nick Kyrgios: Is the 'bad boy' of tennis now the voice of reason?