United, now managed by former Everton boss David Moyes, made a £28m offer for England full-back Baines and Belgian midfielder Fellaini.
But Everton rejected the bid out of hand, describing it as "derisory and insulting" in a statement on Monday.
And Martinez gave his view on Tuesday, saying: "It's been well documented what happened with the transfer speculation.
"That's been dealt with and it was all a little bit of a waste of time, time I don't want the players to waste.
"I'm not a big believer in having the window open while the games are starting. I think the start of the season was important for us at Norwich and I won't come out now and carry on talking about the speculation.
"I think, as a football club, we will always keep our fans informed. When there is something to tell our fans we will do that, they'll be the first ones to know if there are any players coming in or any players going out."
Everton drew their Premier League opener 2-2 at Norwich and Martinez says the club's sole focus is now on this Saturday's fixture against West Brom.
"I don't believe in getting involved in the transfer window when the games are underway and we are in a very, very important moment of our season," said Martinez.
"We're trying to find our feet, we got a good start under our belts, we've got real competition for places, and we've got the visit of West Brom at the weekend.
"The players have had the demands of international football and then they started the league with a lot of travelling.
"So, obviously, you can imagine it's been important these past few days that we can get them recovered, regenerate them in the right manner, and get them ready for the next game. That, at the moment, is our only focus."