The experienced Scottish striker was sent off for catching Wanderers midfielder Josh Scowen with a flailing arm as they battled for possession in midfield
It left Rovers facing an uphill battle and although they fought hard Wycombe substitute Max Kretzschmar netted the only goal eight minutes from time, shooting into an empty net after fellow substitute Jon-Paul Pittman's low drive had been parried by Rovers goalkeeper Steve Mildenhall.
Rovers boss Ward said: "I'm not going to make any fuss about the sending-off, even though I felt it was harsh at the time. These decisions go against you sometimes and I thought the way the team and the supporters responded was excellent.
"There isn't a violent bone in David's body. If anything I wish he was more aggressive at times. But I'll watch it again on film before making up my mind."
Wycombe's Ainsworth added: "There was contact with our player, but I was too far away to see if there was any intent.
"The referee and his assistant have decided that there was and it was obviously a key moment of the game. Having said that, Rovers made it really difficult and were really well organised, as I would expect of a John Ward team."
A game of few chances saw Rovers goalkeeper Mildenhall make the only save of any great difficulty, reacting well to block a 77th-minute shot from Pittman shortly after the substitute had been introduced.
The only moment of anxiety for Wycombe 'keeper Matt Ingram came early on when he pushed a Seanan Clucas header around a post.
Ward said: "I'm frustrated for my players and for our fans because they all put a huge amount of effort into the game.
"We now have to reward those fans by getting something at Accrington on Tuesday night. We are going through a tough time but I have never had cause to criticise the effort put in by my players."