On Monday, UK Foreign Secretary Boris Johnson reiterated the nation’s commitment to maintaining the British sovereignty of Gibraltar, which voted overwhelmingly to stay part of the United Kingdom at a referendum in 2002.
"It seems someone is losing their cool," Dastis said at a conference in Madrid, as quoted by the BBC broadcaster. He added the government had been "surprised by the tone of comments coming out of Britain."
This angered Gibraltar Chief Minister Fabian Picardo who accused Spain of tricking the European Union into "mortgaging" the future EU-Gibraltar ties to its "obsession" with the UK territory.
Gibraltar was ceded to Britain in 1713 but Spain continues to lay claims to the territory on its southern tip, which is home to some 32,000 inhabitants.