The Poland international has netted 35 goals in 44 games for Jurgen Klopp's side this season and made headlines last week as he plundered all four in the German side's stunning 4-1 win over Real Madrid in the UEFA Champions League.
United currently have four international strikers on their books in the shape of Robin van Persie, Wayne Rooney, Danny Welbeck and Javier Hernandez, but the Scot is confident that he could find room for one more.
Ferguson also believes that Bayern Munich's move for fellow Dortmund star Mario Gotze could see their pursuit of the Pole drop off, with Westfalenstadion chiefs not wanting to sell their two star players to their league rivals.
"If the right player comes along you have to be prepared to make a move, I can find room for anybody here as long as they have the required quality," he said.
"I am not sure Lewandowski will be sold to Bayern now. The Dortmund fans are not going to be happy and I don't think they will sell to their main rivals. I think they will either let his contract run out, or sell him somewhere else."
The newly-crowned Premier League champions could not convert their dominance in England to Europe after going out of the Champions League in the first knock-out round to Real Madrid and Ferguson revealed he will look to add stellar names to his squad in order to achieve continental success next term.
May's final of the competition looks set to be an all-German affair with Dortmund and Bayern holding strong advantages over Real Madrid and Barcelona respectively and, despite Jupp Heynckes' side having already won the Bundesliga, Ferguson expects a tight game.
He added: "But for the referee [in United's defeat to Real Madrid] it would have been us facing Dortmund and we would have had to do a good job, because they are a good side.
"Our target for next season is to do better in Europe, possibly by adding a player or two, but it will be interesting if this season's final is an all-German affair.
"I have said all along that Dortmund have been prioritising the Champions League this season. They have an unbelievable record against Bayern so, despite what the German league table might say, if the two sides meet in the final it wouldn't be a gimme for Bayern."