Thiago, 22, was linked with a move to United from Barcelona before opting to join the European and Bundesliga champions.
According to Thiago, David Moyes' men were never in the hunt and he said United had not even made contact.
"The truth is that in no moment did United come to us and talk to us," Thiago told RAC1.
"It came from the press. It was always a lie."
Thiago struggled to break into Barcelona's star-studded midfield for a regular spot, with the likes of Xavi, Andres Iniesta and Cesc Fabregas ahead of him.
But the Spain international dismissed suggestions he was impatient and said game time was all he wanted.
"It's unfair to say I wasn't patient. The club knew my situation. I waited for them, especially before the European Championships, but they never contacted me. I didn't feel valued," Thiago said.
"I wanted to compete. The club knew that I wanted to leave and they didn't do much to change that.
"Everyone looks out for their interests, I wanted to feel valued and I wanted to compete so I decided to leave the club and join Bayern.
"I was waiting and waiting all summer, there was a point when I had to decide.
"All a footballer wants is to play football and I wanted to play, they (Barcelona) didn't do much for me to stay, so here I am."
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