The Cumbrians have lost their last four league games, including damaging defeats to fellow challengers Plymouth Argyle and Portsmouth.
And Saturday's loss to Cambridge saw them concede three goals without reply for the second home game in a row.
"There's a nervousness about the group," Curle told BBC Radio Cumbria.
"There's a nervousness about the supporters as well. They're desperate for us to and the players want to do well to get over the line and finish top three."
Despite the downturn, Carlisle remain fifth in the League Two table, four points behind Portsmouth in the third automatic promotion place, and six points above eighth-placed Mansfield.
But the tough games continue with sixth-place Luton and Mansfield next for Curle's side.
"Teams won't come here and roll over," he added. "So we need to go back to basics, scrap and fight for everything which means we need a level of aggression about us.
"We weren't competitive and aggressive enough [against Cambridge], we weren't demanding with our movement, demanding of the ball.
"There wasn't there that level of confidence going forward, we were disjointed and not on the same page."

The Irish government suggested the formation of the group last week.
But on Monday, DUP leader Arlene Foster said she had not been consulted over it and it appeared it would not go ahead.
But Mr McGuinness has said he does not think "anybody should have a veto on a good idea".
The Irish government government said it proposed the forum to enable groups to work on areas of mutual interest, such as trade, investment and health.
The UK's decision to leave the EU dominated a meeting of the North South Ministerial Council on Monday attended by Arlene Foster and Martin McGuinness.
Mrs Foster said the forum was not on the agenda.
Instead, she said existing cross-border bodies would be used to work out the implications on the island of Ireland of a UK withdrawal from the EU.
On Tuesday, Mr McGuinness said indications from "very senior civil servants within the [Irish] government" were that Taoiseach (Irish prime minister) Enda Kenny would go ahead with the plan.
"I spoke to the taoiseach before the meeting of the North South Ministerial Council - he wasn't putting it as an item on the agenda but he stated very clearly to me that he still believed that it would be a very useful thing to do," he said.
"I wouldn't be too exercised about the fact that there will be political elements who wouldn't be interested in attending.
"The DUP will undoubtedly through different methodologies have their say in relation to all of it."
He said he believed the idea of a forum would "get widespread support from most within the political process".
Government ministers from Northern Ireland and the Republic drew up a list on Monday of priority areas they intend to work on to limit any potential damage of Brexit.
Among the points was an agreement to conduct a "full audit" to "identify the possible impacts, risks, opportunities and contingencies" that the island could face.
And the two finance ministers will "consider the issue of securing" further funding for regional development from the EU.

Alexander Perepilichnyy, 44, collapsed and died in the road in Weybridge, Surrey, on the evening of 10 November 2012.
Surrey Police investigated his death, but decided it was not suspicious.
However, new toxicology tests have shown that a rare poison may have been used to kill him.
Mr Perepilichnyy had told colleagues in London he had received death threats, reports BBC world affairs correspondent Richard Galpin.
He had handed over sensitive documents to a businessman in London and to prosecutors in Switzerland, our correspondent adds.
These implicated Russian officials and mafia members in the theft of $240m (Â£147m) from the Russian state through tax fraud.
The full inquest had been due to get under way earlier, but was delayed because of the new toxicology information.
Tests showed a potential marker for a rare poison called Gelsemium elegans. Further tests will be carried out to establish if the poison was in his body.
Carlisle United need to "scrap and fight" to cope with the pressure of chasing promotion to League One this season, says manager Keith Curle.
[NEXT_CONCEPT]
A proposed cross-border forum on all-Ireland issues in the wake of the UK's decision to leave the EU could go ahead despite not having DUP support, Martin McGuinness says.
[NEXT_CONCEPT]
A wealthy Russian businessman who died suddenly near his home in Surrey may have been poisoned, a pre-inquest hearing has been told.