The Hoops were forced to play with 10 men from the 21st minute after Zamora caught Jordi Gomez with a dangerous, high challenge, and Martinez feels that Dowd had no choice but to show the former a red card.
"If anything, the sending-off went against us. We are a team that enjoy having the ball and we can open teams up but we made it a hard task," Martinez told Sky Sports News.
"It was a horrific challenge. I know Bobby Zamora is not a dirty player but Jordi Gomez is very fortunate - he could have been majorly injured.
"It was the right decision. As much as you don't want to see red cards, that was as much a red card as you are going to see."
The draw has seen Wigan slip into the Premier League relegation zone on goal difference with seven games left to play.