Frank de Boer claimed Inter "played with fear" during the first half of their 2-1 defeat to Atalanta and urged his side to find consistency to turn around their wretched run of results.
An 88th-minute Mauricio Pinilla penalty condemned Inter to their third consecutive Serie A defeat and leaves them marooned in 14th place.
Atalanta led at the break through Andrea Masiello's header and Inter barely threatened in a limp first period.
The visitors improved markedly after the break, and Eder's superb strike looked to have salvaged a point until the dying stages of the game.
De Boer said he has seen plenty of positives during recent defeats, but that the damage was done during the poor first half.
"I am disappointed for the first half, as we played with fear and I don't know why," he told Mediaset Premium.
"I told my players that at half-time and the game changed.
"We know that it is always very difficult to play in Bergamo. Above all in the first half we just didn't play, it was only Atalanta.
"In the second half we did much better, especially after the equaliser.
"It is always difficult when a big club like Inter has three consecutive defeats, but in my view we can improve, as we saw in the second half."
De Boer urged his players to build on their second-half display to produce more consistent performances in future, starting at home to Torino on Wednesday.
"I've seen positive things in many games, but today in the first half it simply was not our Inter.
"We dominated after the break and created chances, so that is the Inter I want to see always."