The 24-year-old Brazil international was the subject of bids from both Spurs and their London rivals Chelsea in the summer, but neither could meet Shakhtar's asking price.
"There were two offers in the summer - one from Chelsea and one from Tottenham," he told Lancenet. "Choosing between the two clubs would be difficult.
"I don't know. I mean, Tottenham are a big club and they have a good person in charge. Andre Villas-Boas wanted to bring me to Chelsea and also tried at Tottenham.
"He always sends me messages. We are always in touch, and he has become a friend, for sure. And Chelsea is Chelsea. They are a great team, with amazing players and are the champions of Europe."
However, Willian insists that he is focused on Shakhtar at the moment.
"I would love to play for either of those clubs," he said. "But my mind remains at Shakhtar, and I'll do my best to get the win against Chelsea.
"Everybody knows what my goal is. I've clearly stated that I would like to play in a bigger stage, whether it be England, Spain or Italy.
"I want to come back to the national team, and being in a bigger spotlight would help me get noticed."