Villas-Boas told ESPN that he was an admirer of the Mexican international while at White Hart Lane, adding that talks eventually broke down between the pair.
"I was close to signing Chicharito, I still have a very good relationship with him," the 40-year-old said. "He always said: 'Coach, I'm going to fight for my position [at United] and I'll fight until the end.'
"I told him that he should give me an opportunity that he should come, but no. He believed in himself a lot and that also excited me.
"In the end we weren't able to come to an agreement."
Hernandez was sold to Bayer Leverkusen when Louis van Gaal became United manager, before the striker moved back to the Premier League with the Hammers last summer.