If you watch the following video of the incident from the CBC you can interpret it as you like.
Here's another view to consider when watching this unfold (warning this is highly political and speculative). A vote was being held that the Liberal party (of which Mr. Trudeau is head) was trying to get pushed through. The opposition was unhappy about this and the NDP party members were attempting to delay the vote, physically standing in the way of the Conservative party whip, preventing him from voting. Mr. Trudeau went over to the NDP representatives and grabbed the Conservative party whip to help him through the physical blockage created by the NDP members, and accidentally elbowed a female NDP MP in the process.
Giving Mr. Trudeau the benefit of the doubt, he could have had a combination of several motives for this: he could have wanted to speed up the vote he was trying to push through, or maybe he didn't want to allow the NDP to impede democracy by blocking another voter (the Conservative whip), and he wanted to ensure a colleague in the House got to vote.
Naturally the NDP MP, who had been elbowed, was upset. I would be too, but it seems that perhaps too much was made out of this, on the NDP's part. Sadly, the Conservatives (who arguably benefited from their whip being able to get through to vote) lashed out as well, in true partisan style. It was Green Party leader Elizabeth May who defended Mr. Trudeau, even across partisan lines. Mr. Trudeau himself even apologized for the incident.
Was Mr. Trudeau completely innocent? No, after all, it's debatable whether or not he was helping the Conservative whip at all. The whip was perfectly capable of going around the other side of the aisle, or pushing through the NDP crowd himself. It was not the responsibility of the Prime Minister to jump in physically. After all, the physical action of the NDP blockage was what Mr. Trudeau was protesting when he acting. The House of Commons, a forum of ideas, is hardly the place for physicality. But let's put things in perspective here, even if I don't agree with Mr. Trudeau's politics, let's keep it to his politics, the man is a human being as is every other member of the House of Commons. We all make mistakes, the important point is the motives and the restitution of the action. I don't believe Mr. Trudeau intended to physically hurt anyone, and I think we need to look past partisan lines and move on to bigger issues that shape Canada as a whole.
Whether you are Canadian or not, and regardless of the political party you favour, prayer for our House of Commons, our government, our Prime Minister and opposition leaders would be deeply appreciated.