Reuben Reid scored the only goal of the game eight minutes from time at Home Park, which condemned the Pirates to their second defeat of the League Two campaign.
"It was frustrating," PA quotes Ward as saying. "We fizzled out in the top third of the pitch and we haven't worked their keeper enough times for me to sit here and claim we could get a draw.
"At this moment in time there are not enough goals in my team and we need to work hard to improve in that part of the pitch.
"They have won the game and I am fine with that and I am not making any excuses and I want to stress that. I am not shouting and screaming but I still expect a bit more from the team in the top half of the pitch."
Rovers are currently 11th in the table after five games.