Recent forecasts that demilitarisation will be speeded up would put back chances of a political deal, Ian Paisley has said.
Mr Paisley said he would have to "swallow hard" to do business with republicans
The DUP leader said it was not up to his party to say yes or no to the latest British-Irish proposals when they meet Tony Blair on Monday.
Instead, he said Sinn Fein should first indicate that they would abide by the governments' proposals.
Mr Paisley was speaking after meeting Chief Constable Hugh Orde on Friday.
He said that if the IRA gave up its weapons and abandoned its criminal activity he would have to "swallow hard" to do business with republicans.
"Once they quit their terrorist path, I will have to do a good deal of swallowing," he said.
"I'll have to do a good deal of biting my lip in future days."
Later, Sinn Fein President Gerry Adams responded angrily to Mr Paisley's remarks.
"Ian Paisley's outburst tonight can only make the achievement of agreement
more frustrating. Perhaps that is the intention," he said.
"The use of such provocative, insulting and offensive language is the
clearest evidence of how far the DUP have to move to embrace concepts of
accommodation and equality which are at the core of the peace process."
There have been intensive negotiations between the two governments and the political parties over the past few weeks.
They have centred on the responses from Sinn Fein and the DUP to the proposals put forward by the British and Irish Governments aimed at restoring power-sharing in Northern Ireland.
The current negotiations are being conducted through a series of British and Irish Government intermediaries because the DUP refuses to hold face-to-face talks with Sinn Fein.
Sinn Fein has said it believes a deal is possible. However, the DUP has told the IRA a deal was "now or never".
On Thursday, Mr Adams urged Mr Paisley to accept the proposals adding that both governments are very clear about Sinn Fein's position.
But he said if the DUP leader believed it was "now or never" for a deal he should say yes to the latest British and Irish proposals.
He has also again declined to comment on the details of decommissioning and photographic evidence which has been demanded by the DUP.
He claimed this was a matter for General de Chastelain's arms commission.
The leader of the moderate Alliance Party has said a political agreement in Northern Ireland could be reached by the middle of next week.
David Ford has said moves are being made in the right direction.
Mr Paisley met the prime minister on Tuesday to discuss his party's response to the proposals.