Beckham is set to play for $8.5 million on the fifth-year option of his rookie deal.
"I wouldn't say sense of urgency. The contract will get done when it's supposed to get done," Mara said Tuesday at the 25th Anniversary Gridiron Gala held by the United Way of New York City.
"I think that is the [general manager] Dave Gettleman line. I think I'm going to adopt that. All spring, all summer, as long as it takes."
Beckham still hasn't been cleared for practice after fracturing his ankle in a Week 5 defeat to the Los Angeles Chargers in October.
Mara also insisted that he isn't worried if the three-time Pro Bowl wideout elected to sit out through training camp and even the preseason.
"It's not the first contract negotiation we've had," Mara said. "It will get done when it's supposed to get done."
The Giants start OTAs on May 21 and have another three-day minicamp in mid-June.
The team slumped to a 3-13 record with Beckham primarily on the sideline last season, and the offense finished 31st in the NFL in scoring at 15.4 points per game.
Beckham has 313 catches for 4,424 yards with 38 touchdowns in four seasons with the Giants. He was named the 2014 Offensive Rookie of the Year.