Gemili, who was just three thousandths of a second outside the medals at Rio 2016, was hampered by a hamstring problem as he came sixth in Birmingham.
"I didn't want to race, but the powers-that-be said if I wanted to make the team I had to," said the 23-year-old, who will be part of the 4x100m squad.
"I was trying to run with one leg."
The three-time European gold medallist had been struggling with a hamstring injury since the World Relay Championships in the Bahamas in April.
British Athletics declined to comment on Gemili's claim.
As the first two finishers in the race on 2 July, Nethaneel Mitchell-Blake and Danny Talbot took the automatic qualifying places for the 200m.
Zharnel Hughes, who finished fourth in Birmingham and has a quicker season's best than Gemili, was named as Britain's third representative when the team was announced on 11 July.
Gemili said: "I had a terrible race and I could have stopped, maybe I should have, but I was too proud to go out there and pull up."
He missed another chance to impress the selectors when he pulled out of the Anniversary Games, which were staged seven days after the British trials.
And Gemili's appeal to selectors to reassess his form before 24 July - the deadline for World Championship teams to be finalised - was declined.
British Athletics performance director Neil Black said at the team announcement that "performance in the trials and recent performances meant we chose Zharnel ahead of Adam".
Gemili said: "I'm completely fit now and, because I told them I would be, that's annoying."
The World Championships begin in London on 4 August.
"Missing the chance to run in front of a home crowd is gutting, it's heartbreaking," Gemili told BBC Sport.
"But I have learned a lot about myself, my body and the people around me. I have got to take the positives from it."
Adam Gemili claims he was forced to run at the British trials while injured, as he unsuccessfully tried to secure a 200m place for the World Championships.