The Justice Secretary, who defied the Prime Minister to support a Leave vote, said that Euro judges could ignore his highly publicised changes.
Mr Gove warned that the European Court of Justice will have the final say on the changes, which have failed to satisfy the Eurosceptic movement.
Rules to restrict migrant benefits are thought to be particularly at risk if the court decides they amount to discrimination.
It comes as voters turned on Mr Cameron”s touted concessions, with three quarters saying they fail to impress.
Mr Gove issued a dire warning that the European Court of Justice, which sits in Luxembourg, “stands above every nation state” and is free to ignore the changes.
He told the BBC: “The first thing is the prime minister is right – this is an agreement between 28 nations and all have agreed that they will abide by it.
“But above those nations sits the European Court of Justice.”
The intervention is the first since Mr Gove, a close personal friend of Mr Cameron, came out for Brexit this weekend.
He posed alongside fellow cabinet rebels Chris Grayling, Iain Duncan Smith, John Whittingdale, Theresa Villiers and Priti Patel with a banner saying “Let”s take back control”.
They were soon joined in the Out campaign by London mayor Boris Johnson, who infuriated the Prime Minister by flying the flag for Brexit.
Pollsters believe that Mr Johnson”s intervention could make the crucial difference in persuading voters to quit the EU for good.
Mr Gove”s intervention followed more bruising news for the Remain campaign.
A poll released Monday said that three quarters of voters do not think migrant benefit curbs – the centrepiece of Mr Cameron”s deal – will cut migration.
Some 75 per cent of respondents to a ComRes/Daily Mail poll said numbers coming into the EU will either stay the same or increase after the changes.
Sixty per cent of people said that levels of UK immigration – currently some 180,000 a year – is too high and must be dealt with.
And almost half of those polled recognised that quitting the EU altogether is the only way to clamp down.
Downing Street tried to shut down speculation sparked by Mr Gove”s intervention.
But they could not deny that the ECJ has the power to dismantle Mr Cameron”s deal – saying only that it must “take it into account”.
A spokesman told Express.co.uk: “It is not true that this deal is not legally binding.
“Britain”s new settlement in the EU has legal force and is an irreversible International Law Decision that requires the European Court of Justice to take it into account.”