Wallace has recently returned to the matchday squad after a lengthy time on the sidelines while Rossiter has also struggled with a series of injuries since joining from Liverpool.
Neither pair were named in the player list for the Europa League group matches against Villarreal, Rapid Vienna and Spartak Moscow.
But Gerrard has outlined why the pair were left out.
Spekaing ahead of Rangers’ home match with Dundee, Gerrard said: “[Jordan and Lee] are coming off the back of playing very little football, so it makes no sense to congest their game plan.
“There is no way Lee or Jordan would be able to play Saturday, Thursday, Sunday, for example.”
The former Liverpool and England midfielder added: “We want to help those players, and try to find a schedule that suits those two at the moment.
He continued: “I think, for the short term, that will be one game a week at the minute.”
Looking ahead to the visit to Ibrox of former Ger Neil McCann with his Dundee team, Gerrard revealed that Lassana Coulibaly should be fit but his midfield colleague Ryan Jack is a doubt with a calf injury, with recent signing Gareth McAuley nursing a similar complaint.
Gerrard said: “Lassana is back, fit and available, and he will be involved tomorrow. We are really pleased to have him back as we have missed him a lot.
“We are a bit mixed at the moment as we have had a couple of injuries off the back of international duty.
“Unfortunately Ryan has got a calf problem which we are assessing, and Gareth has also returned with a calf problem, which is a bit of a blow for us, but we will get on with it.
Winger Eros Grezda, who missed his country’s Nations League match with Scotland on Monday night, stands a slim chance of making the matchday squad.
Admitting that the player’s match fitness was still a bit of an issue, Gerrard continued: “He is nearly there - he might be involved tomorrow, but we will make that decision in the next couple of hours.
“First and foremost, we are delighted to have him as he is a top player and a very exciting player.
“He has pace, a lot of ability and I’m sure the fans will love him when he is up to speed.”
Describing Grezda as “around 70 - 90 per cent”, Gerrard added: “He had surgery on June 6 so we are still trying to progress that, move him forward and also his match fitness.
“We haven’t got game time to give him in terms of pre-season games so we will try to press forward with his progression, so he may be involved tomorrow, we’ll have to wait and see.”