Vettel drove for the Faenza-based team when it was known as Toro Rosso before moving to Red Bull and winning four world championships prior to leaving for Ferrari.
He remains on friendly terms with the Milton Keynes-based team and its boss Christian Horner.
Speaking in an ITV interview at Goodwood on Saturday, Vettel stressed that he is happy to see his former team-mate Daniel Ricciardo make a return to the grid, but said that the turn of events was unfortunate for De Vries.
When asked for his thoughts on the AlphaTauri news, Vettel said: “Twofold if I'm honest.
“I'm very happy for Daniel, very happy. I like him, obviously I raced with him, and I met him at the test when I was shaking down the [1993] McLaren for this weekend. And I'm very, very happy for him.
“On the other hand, you have to be honest as well. It's obviously a shame for Nyck, the way it comes to an end. I think he was given a great chance.
"Maybe things didn't happen for him the way he expected, or people expected. But it's also a bit harsh when it comes to a very sudden stop like that. It's brutal.”
Vettel said he hoped that De Vries’s departure from AlphaTauri won’t have a long-term impact on his career.
"I met him last year for the first time and he seemed like a really good person, and he is a good driver,” said the German.
“He won the F2 championship, he won international championships. So he's well recognised and I hope that this sort of dent doesn't give a dent to his career. People stend to do that, and that's not right.
“Maybe those 10 races didn't go according to how good they could have been. We don't know why, first of all, from the outside, and second, he is still a very good driver.
"So I have to also sympathise with the fact it's very harsh for him, and I hope that people don't see that dent.”
Meanwhile, Vettel's former team-mate Mark Webber said he’d advised Ricciardo not to leave the Red Bull camp at the end of 2018, and cautioned that his fellow Australian will quickly have to get up to speed with new AlphaTauri team-mate Yuki Tsunoda.
"I was keen for him to stay in Red Bull, I think he know that all those years ago I was trying to talk him into staying,” Webber told ITV.
“But obviously he was keen to go to Renault at the time, and then he went to McLaren, he's had a year out, and now he's back.
“The stopwatch never lies, you're either giving pressure or you're taking pressure. So now he's back on the grid and obviously he's got to step up against Yuki pretty quickly, and hopefully he can perform well."
