Mascarenhas has not played first-class cricket since September 2009
Hampshire have fined all-rounder Dimitri Mascarenhas £1,000 for his Twitter comments about England national selector Geoff Miller.
The 32-year-old used expletives when describing Miller on Sunday.
"I realise that my actions were stupid and irresponsible and I regret any offence I may have caused," Mascarenhas told the club's website.
"This was a late-night conversation that got out of control and does not reflect my true views on Mr Miller."
Mascarenhas, who has played 20 one-day internationals and 14 Twenty20 internationals, is currently out of action with a long-term Achilles problem.
There is little point in imposing a ban, given the long-term nature of his injury
Hampshire chairman Rod Bransgrove
"I apologise specifically to Geoff Miller who has always treated me fairly. I also apologise to Hampshire whom I feel I have let down," he added.
"I have learnt a great deal about the dangers of social networking sites and encourage other players to think carefully before signing up to them."
Hampshire chairman Rod Bransgrove said: "The fine has been set at this high level as I feel there is little point in imposing a ban, given the long-term nature of his injury.
"In coming to this conclusion I have taken into consideration Dimi's previous exemplary record. However, as club captain he understands that his actions carry more responsibility than others."
The fine handed down to Mascarenhas comes on the same day that batsman Kevin Pietersen was fined an undisclosed amount for comments he made on Twitter after being left out of the England one-day squad.