Clare general election candidate Richard Cahill said workers have been contacting him fearing the operation is under threat and their jobs could be lost.
Aer Lingus has confirmed it will undertake the review in 2016 but said it is not possible to speculate on the outcome.
International Airlines Group (IAG), headed by former Aer Lingus boss Willie Walsh, completed a successful takeover of the Irish carrier earlier this year.
“The cargo facility has been put under performance review for the first quarter of 2016 and staff have told me they are feeling decidedly nervous about this situation despite recent records showing that Shannon is a more financially efficient operation than its Dublin counterpart,” he said.
Mr Cahill said he has seen communications from Aer Lingus chief executive Stephen Kavanagh to minister Gerald Nash, dated May 27, as well as emails from Mr Kavanagh dated June 2.
All of these communications seek clearly to assure staff of the security of their tenure of employment while seeking shareholder approval.
Mr Cahill has called on IAG to “clarify to the relevant Shannon-based IAG staff that the upcoming review will not have any effect on their tenure of employment.
“This is the least they deserve and no worker should have to worry about whether they will lose their job especially so close to Christmas ,” he added.
An Aer Lingus spokesman said: “Aer Lingus will review its cargo operations at Shannon next year.
“We constantly review all aspects of our business from commercial and operational point of view, across all of our bases.
“The outcome of the review at Shannon is not pre-determined and it is not possible to speculate any further,” the company added.
IAG has previously stated: “Under IAG’s structure, Aer Lingus, as with all the airlines in the group, is responsible for its own operation.”