Mr Adams has been criticised for the online video in which several of the Provisional IRA's best known phrases are used.
The video, which has now been withdrawn, featured the former Sinn Fein president singing "Tis the season to be jolly, tiocfaidh ar la, la, la, la, la" while another character repeats the phrase "They haven't gone away you know", famously used by Mr Adams in 1995 in reference to the IRA.
Taoiseach Micheál Martin has led calls for Mr Adams to apologise.
Speaking to the PA news agency, Sinn Fein leader Ms McDonald said: "The video was for Foyle Rescue, it was for a very, very good cause.
"I just think it's a terrible pity that something that's done, for the best of reasons and with the best of heart, has resulted in this controversy.
"I think the video has been withdrawn. I think that was the right thing to do.
"And then as regards Sinn Fein, people will have different views on on this, you know, we don't have a party position on it.
"But as far as I am concerned, I wouldn't be asking somebody, anybody, Gerry Adams or anyone else to apologise for doing something for a good cause and with a good heart.
"I just think that that wouldn't be a reasonable position."
Troubles victims including Ann Travers, whose sister Mary was shot dead by IRA gunmen in 1984, have criticised the video.
The Derry-based business Ferry Clever announced on Sunday it was withdrawing the video and card.
Prominent Sinn Fein members, including vice-president Michelle O'Neill, and health spokesperson in the Republic David Cullinane, have insisted Mr Adams has "nothing to apologise for".
However, housing spokesman Eoin O'Broin has said the former party leader should apologise "for the offence caused".
Asked if Mr Adams should not have foreseen that the phrase "they haven't gone away you know" could cause hurt to IRA victims, Ms McDonald replied: "Well, they have gone away, you know.
"The IRA has gone away and the war is over. The war is over, the conflict is over, thank God."
She added: "We now move forward. And I suppose if there's a lesson in all of this, it's a lesson of people being 'anna curamach ar fad' (very careful indeed in Irish) - very careful with what they say and how it might be heard.
"But let me repeat, and I think this is important to say, this was a video for a really good cause.
"It was intended as satire and almost a sending up of Gerry, if anything."
With Sinn Fein gearing up for a place in Government, Ms McDonald suggested the use of such slogans would not be acceptable from her current party members, saying she "runs a tight ship".
Mr Cullinane caused controversy in 2020 when he was caught on camera saying "up the Ra" after his re-election to the Dail.
"At the time, David apologised for that, and he was right to. It was very ill-judged and in an unguarded moment," she said.
"I think I've made my position clear on that. I expect all of our people in leadership positions to do their job diligently, efficiently, honourably.
"And not to get themselves involved in distractions or cause upset, that's my expectation.
"I have to say, nine times out of 10, 99 times out of 100, our team and our people are at that standard.
"Then, at times, people make mistakes, they speak out of turn. That's it."
Asked if there would be consequences for Sinn Fein ministers if they used such slogans in Government, she said: "Well, I don't envisage a Sinn Fein minister using those kind of phrases.
"I run a fairly tight ship. I mean, people know that I expect people to get on with their work.
"For people who speak out of turn, or suffer from foot-in-mouth syndrome, of course, I expect them to correct for that behaviour.
"Anybody representing Sinn Fein, I expect them to do their work well, do it honourably, to be accountable, all of those things."
Asked if the same standards of accountability did not apply to Mr Adams, she said: "Gerry is retired and Gerry can speak for Gerry."