Scotland's First Minister Alex Salmond believes Prime Minister David Cameron's decision to veto EU treaty changes could affect talks on fish quotas.
He told the BBC that Mr Cameron's "irresponsible posturing" could make it harder to stop regulation of the Scottish fishing industry.
Mr Salmond has written to the prime minister asking him to explain his actions to the devolved governments.
Only the UK rejected the Lisbon Treaty changes to tackle the eurozone crisis.
At a summit in Brussels on Friday, Mr Cameron used his veto to say no while the other 26 member state heads voted for the package of measures.
The Tory leader and Chancellor George Osborne have insisted the veto was used in part to protect the City of London from excessive intervention by Europe, but Labour and the UK Independence Party (UKIP) have both argued that no additional safeguards were achieved.
Mr Salmond told the BBC's Today programme: "We have vital fishing talks in Brussels this week - is it going to be easier or harder to obtain the support of the countries we need to fend off regulation which would be disastrous for the Scottish fishing industry? I do think it will be harder."
He added: "It is vital, absolutely vital, that the eurozone is stabilised, whether you're in or out of the eurozone, it's absolutely vital to our national interest, to the Scottish interest, to the UK's interest incidentally, that the eurozone is stabilised."
The new accord aims to hold eurozone members to strict budgetary rules including: