The New Zealander was dropped last week to Red Bull's junior team, Racing Bulls, and Japanese driver Yuki Tsunoda has been promoted ahead of his home Grand Prix at Suzuka this weekend.
"It was definitely a shock, honestly. It's not something that I saw coming," Lawson told Sky Sport F1.
"The discussions we were having as well, I think, weren't really leaning in this direction, so it was definitely not something that I sort of expected."
Red Bull has come under fire for dropping the 23-year-old after just two Grand Prix this year - in Melbourne and Shanghai - in which he performed poorly. Many pundits have described the Red Bull car as difficult to drive.
Lawson was asked whether he was frustrated at the lack of time he was given in the top team.
"Honestly, yes. Obviously, I would have loved more time.
"And I felt like with more time, especially going to places that I'd been before… it was a tough start. We had a rocky testing. We had a rocky first weekend in Melbourne with practice. And then obviously China was a sprint.
"I think going to places that I'd been before with the way the car was quite tricky, I think that would have helped and I would have loved that opportunity. But obviously, it's not my decision, so I'm here to make the most of this one.''
Lawson spun out late in the Melbourne race after qualifying 18th of the 20 cars, while in Shanghai he qualified in last place for the sprint and the main race, finishing with 14th and 12th places, respectively.
Red Bull principal Christian Horner told Sky Sports he had asked too much of Lawson too soon.
"Of course, it's horrible because you're taking away someone's dreams and aspirations, but sometimes you've got to be cruel to be kind, and I think that in this instance, this is not the end for Liam.
"I was very clear with him, is that it's a sample of two races. I think that we've asked too much of you too soon."
Verstappen hints at Honda
Red Bull's main driver, four-time world champion Max Verstappen, has hinted at a future relationship with Honda after the Japanese engine maker's highly successful partnership with Red Bull finishes at the end of the Formula One season.
Reuters reports Honda engines have fired the 27-year-old Dutchman to four successive world titles with Red Bull, but from 2026 they will be powering the cars of the Aston Martin team.
At a Formula One fan day run by Honda in Tokyo on Wednesday ahead of the Japanese Grand Prix, Verstappen expressed his gratitude.
"It's been a ride that I enjoyed a lot," he told fans after driving the RB16B, the car in which he won his first world title, on the streets of Tokyo.
"Of course before we started working with Honda, we had our success. But I could have never imagined the heights that we got to, winning four championships together.
"I want to try and just enjoy the weekend, try to go as fast as you can, but it's more about also just remembering all that we have achieved together in the sport and who knows, of course, in the future as well?
"You know what can be done. So it's like a goodbye for now, but that's it. I'm still quite young and you never know what happens in the future."
Verstappen's comments will further fuel speculation that he may not see out his contract at Red Bull, which runs through the 2028 season.
Media reports have suggested that the Dutchman has performance-related exit clauses that would allow him to leave if the Red Bull car was not competitive.
Former F1 driver Juan Pablo Montoya told Vision4Sport on Tuesday that he thinks Aston Martin, who have already recruited car designer Adrian Newey from Red Bull, would make Verstappen a hugely tempting offer if he had cause to trigger those clauses.
"I think Max will get an offer he can't refuse from Aston Martin," the Colombian said.
"If I were Max, I would go to Aston. Mercedes would be cool too, but Aston would be the logical choice, having Adrian and Honda. Everything he has won with is there."
Japanese Grand Prix
Starts: 5pm Sunday, April 6
Suzuka International Circuit
- RNZ Sport and Reuters
