Robinson made a number of changes to his starting line-up following their disappointing display at Sunderland in midweek.
He was largely happy with the performance of his side but was once again left to rue some poor defending at vital times.
Portsmouth became the latest opponents to score against the Shrimps from a corner with goals from Marcus Harness and Connor Ogilvie giving the home side three points.
Morecambe’s defeat was their eighth in the last 11 league games and saw them drop into the League One relegation zone ahead of Fleetwood Town’s visit to the Mazuma Stadium on Saturday.
Robinson said: “The defeat was a difficult one to take.
“I actually thought it was a very good performance at times.
“It’s hard to sit here and say that when you’ve lost 2-0. We’ve come here and dominated large areas of the game, played in areas we wanted to play in.
“I thought we played well in the first half, even better in the second half.
“After a 5-0 defeat in midweek, it was a case of trying to regain confidence which the lads did, so it’s hard for me to criticise the players too much really.
“We played with energy and commitment against one of the best sides I have seen in this league this year, and that was good, but we conceded from another set piece at a bad time and that was really disappointing again.”
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