The combative midfielder was sent off for the second time this season late on in Saturday's FA Cup quarter-final victory over Chelsea.
Barry was booked for his involvement in the fracas that saw Diego Costa receive a second yellow card and then followed suit three minutes later after fouling Cesc Fabregas.
Because it was the 35-year-old's second red of the campaign he must serve a two-match ban, ruling him out of the high-profile Premier League clashes with Arsenal and Manchester United.
Martinez told evertontv: "We are quite strong in every department - that's what's pleasing. We never look to have excuses for having players not available. We'll never go down that route.
"The squad is ready and players have been working really hard. It's going to be great to see what a new partnership can bring to the side
"But, clearly, Gareth Barry has been an incredible influence in the last three seasons, none more so than in this campaign, where he has been involved in every Premier League game.
"He is going to be missed but the challenge we face is can we perform in a really positive way, even when Gareth is not on the pitch? We have to rise to that."
Source: PA