The New Zealand captain has been criticised by some for not approaching O'Driscoll as he was being carried off with a dislocated shoulder sustained in an off-the-ball incident which saw Umaga and All Blacks hooker Keven Mealamu up-end the Irishman in the opening moments of the match.
However, Umaga insisted it was right his focus had been on his team during the long injury break and not on O'Driscoll.
"I had to try and keep them together. We were obviously talking about things that we could do,' he said.
"It was such a lengthy period and we had to sort some things out that were better for us.
"First and foremost my allegiance is to the All Blacks and that's the way it is."
Umaga did not offer an explanation as to how O'Driscoll had found himself upside down with both legs in the air but made it clear it was not a deliberate act and that O'Driscoll's departure, on the back of losing experienced duo Lawrence Dallaglio and Richard Hill, was a sad one for the tourists.
"I think it's too late for explanations now. Everyone has got their own ideas about it. It's Wednesday we've got two more days to try and prepare for a game," he added.
"I could try to explain it but what would that achieve. I think everyone has made their decisions."
The 32-year-old expressed surprise the incident was still such a hot topic of debate four days after it had happened, especially since he and Mealamu were never cited.
He also confirmed he would be seeking a one-on-one meeting with O'Driscoll. The pair have traded telephone messages.
"It [the incident] was obviously dealt with by the people that had to deal with it and I felt that that was the end of it, other than maybe having a word with Brian himself person to person. I've never had the opportunity as yet [to do that] but, who knows, that might happen.
"I asked some of the Lions players after the game [about how Brian was] but again I don't try and do things through the media. We will try to make contact and when we do, we will. It's just how I am."
Umaga denied suggestions the Lions' unique approach to the haka - which saw them fan across the field from touchline to touchline with O'Driscoll picking up blades of grass as the haka finished - had annoyed him.
"It just caught us on the hop and was different. Each team has their own way of approaching the haka," he said.
After a difficult and emotional week Umaga is keen to switch his focus back to the rugby and the second Test in his home city of Wellington.
It is a clash which could see the All Blacks clean up the three-match series, although that is not something the captain has not had time to dwell on.
"It hasn't really come into my mind as you can imagine there have been other things," he said.
"But in a perfect world it would be great to finish it up here playing on my home ground in front of my home crowd and in front of my family."
Lions coach Sir Clive Woodward has named seven new players in his starting line-up for this weekend's match and Umaga dismissed the notion that was a sign of desperation.
"They are a team who are able to do that. They are not calling on players who haven't played international rugby before," added Umaga.
"They are all internationals so they have played at the highest level and that is the level we are playing at now.
"It's nothing new for them. They have been together for a while now and they have grown to know each other."
And Umaga insisted the Lions were far from being a spent force despite last weekend's less than satisfactory performance in the 21-3 defeat in Christchurch.
"We all know that once something is backed into a corner and has no other way than to come out fighting that's when they're at their best," he said.
"I don't think we're taking anything for granted. I think we're ready for probably a bigger test this week because everyone's against them."