The Nerazzuri went to Marassi on Wednesday with a fringe side, and the defeat meant that Inter have conceded six goals in two games, after the 3-3 league draw with Roma on Sunday.
"Once again we conceded a ridiculous goal, then from a set play that we ought to know how to defend against and yet another ridiculous goal," Mourinho said after the game.
"Defensively we are giving too much away and aiding our opponents."
Rivas Defence
Nelson Rivas, who had a horrible first half against Manchester united in the UEFA Champions league last week was once again given the nod to start at Samp.
However, the Colombian was at the centre of attention when he was robbed by Antonio Cassano, allowing the forward to score Sampdoria's first.
"Rivas didn't do well, he knows that and we all do," The Portuguese coach added.
"But I don't think it is right to focus on him, as there were 11 players on the field and a Coach on the bench, so we all lose and win together."
Watch Sampdoria vs. Inter goals