Martial became the world’s most-expensive teenager on deadline day after joining from Monaco in a deal that could be worth up to €80 million (£59m).
"Anthony is a very good player, I played with him at Lyon,” Fekir told Europe 1.
“Of course, it's a lot of money. We know that clubs are capable of spending these amounts on good players.”
Fekir has started the season in sublime form for Lyon with four goals in as many matches, including a hat-trick in the 4-0 win over Caen last Saturday, and the 22-year-old, who has been linked with Arsenal, would relish the chance to follow Martial to the Premier League.
"Playing for Manchester United one day? Why not. it's a club that makes you dream, but we're not there yet,” said Fekir.
“The need to have a good season at Lyon comes first, and then, we'll see.”