The outcome at the Stadio Olimpico allowed league leaders Juventus to head into the winter break with a three-point advantage over Roma at the top of the Serie A standings.
Juve had seen Roma close the gap to just one point last weekend, but extended their lead thanks to a 3-1 victory at Cagliari on Thursday.
“We found ourselves up against a very defensive-minded Milan side,” Garcia told Roma’s official website. “We should have done better.
“We had the chances to score but should have tested the keeper more.
“I consider this result a step back and two dropped points.”
For the first time this season, the Giallorossi failed to score at the Stadio Olimpico in Serie A.
Milan were reduced to 10 men for the final 20 minutes after Pablo Armero was sent off after picking up a second booking but Roma were still unable to find a way through.
“Milan defended well,” Garcia said. “They left little space between the lines and kept things tight with five men in midfield.
“We needed to be a bit more creative but we lacked that without (suspended midfielder) Miralem Pjanic.”
The result could have been somewhat different, according to Garcia, had Roma been awarded a first-half penalty after AC Milan’s Nigel de Jong appeared to deflect Gervinho’s header with his hand in the area.
However, the referee did not see the incident and waved play on, much to Garcia’s frustration.
“It’s not the first time I’ve said this: if we have goal-line assistants then they have to take responsibility for decisions, otherwise there’s no point in having them,” he said.
Despite Saturday’s setback, Garcia, whose side will take on Feyenoord in the last 32 of the Europa League, insists his team have plenty to look forward to in 2015.
“We’re in the running on three fronts (Serie A, Coppa Italia and Europa League),” Garcia said. “We’ll do everything we can to win.
“I hope the guys come back from the holidays utterly determined and with the same hunger we’ve shown in the first five months of the season.”
AC Milan coach Filippo Inzaghi praised his team’s fighting spirit as they held on for a valuable point in Rome.
“I am very proud of my team and happy with the result,” Inzaghi said to www.acmilan.com. “More so considering we had to play in numerical inferiority for the final 20 minutes of the game.
“Before the red card I thought we were controlling the game and we could have even won it.
“A few months ago I never would have thought we could come here and play on such level terms with Roma.
“If you don’t come here and play with this heart, you are going to lose against Roma.
“I am immensely proud of my players.”
The outcome followed Milan’s 2-0 triumph over Napoli and lifted the Rossoneri to seventh place, 14 points adrift of Juve.