The property loan portfolio was sold to the Cerberus investment fund in 2014 for more than £1bn.
The Deputy First Minister was giving evidence to the Irish parliament's Public Accounts Committee (PAC).
Mr McGuinness told the PAC he had been "excluded" by Peter Robinson.
He said the events surrounding the sale were at a time when relationships between the DUP and Sinn Fein were "appallingly bad".
Nama is the Irish government agency set up to manage loans acquired from Irish banks after the property crash.
Ireland's auditor general found there were shortcomings in the sales process of the Northern Ireland portfolio.
Mr McGuinness said he had not been informed about meetings and contacts between Nama, bidders for the portfolio and DUP ministers in the run up to the sale.
He said a "determined effort" was made to prevent access to information.
Mr McGuinness made similar remarks when he gave evidence to Stormont's Finance committee last year.
He faced criticism from some PAC members for what they said was his "hands off approach" to the portfolio sale.
There were tetchy exchanges when Labour member Alan Kelly accused Mr McGuinness of "wilful neglect" and steering clear of the issue in case it would be "toxic" for Sinn Fein.
Mr McGuinness said that was "total and absolute rubbish" and accused Mr Kelly of "grandstanding for the TV cameras".
Representatives from Cerberus are due to give evidence to the PAC on Thursday.
The Public Accounts Committee also said it has couriered an invite to Peter Robinson to invite him to give evidence to the Nama inquiry.
It said it had previously tried to contact the former First Minister via the DUP but Mr Robinson said he had not received an invite.
In a statement to the Press Association, Mr Robinson said he is not answerable to the PAC.
However the statement added that he "would want to be helpful".
Martin McGuinness has reiterated that he had limited knowledge of the controversial process around the sale of Nama's Northern Ireland portfolio.