Mascherano, along with Argentina teammate Carlos Tevez sealed a surprising move to West Ham United from Brazilian club Corinthians in the last day of the summer transfer window.
"We were never interested in Tevez. Mascherano, we were offered him," Gill was quoted as saying by Sky Sports Network.
"We were offered him at the start of the summer transfer window for a significant sum. The manager and his staff did not want to pursue that.
"We were also offered him towards the back end of last week in a loan-type deal for a year, and again we were not interested in that," he added.
United were looking to reinforce their squad after the retirement of former skipper Roy Keane left a void in the team's midfield.
The Red Devils signed Tottenham's Michael Carrick for $33 million and failed to acquire the services of either Villarreal's Marcos Senna and Bayern's Owen Hargreaves.
Despite United's demands in midfield, they decided Mascherano won't be the man they are looking for.
"Mascherano we watched closely and very carefully and the experts on that area in our club determined that we did not want to go for him," Gill said.