The 32-year-old Argentine praised Andre Villas-Boas' side, conceding that it will now be very tough to progress to the quarter-finals.
"Our opponents were better and not only physically," Cambiasso told the club's official website.
"You can't just criticise us for not matching up to them physically, we have to congratulate the winners and aim to turn the tie around, even though it's not going to be easy. We had a few chances, but they were clearly on another level."
His Inter team-mate, Christian Chivu, was equally impressed with the North London side, although he admitted his team made too many errors.
"We must hope we can hit the right vein of form in the return leg. They were a notch above us in everything tonight.
"We keep doing badly in the first half. I don't think it comes down to a lack of concentration. Every game is a different story. It's true that's been happening to us a lot us lately but our determination hasn't changed," he said.
But the Romanian admitted added that the Europa League is not necessarily his side's number one priority this season, explaining: "For the club and for the team, getting back into the Champions League is obviously an important target.
"But I think it's hard to say what our primary objective is."