"I've made my decision about Braga. As for the rest, we will see later," Domingos told a news conference as he declined to comment on media reports he will coach Sporting next season.
His success in leading Braga to their best league finish of second place last year and their first European final this season had led to intense speculation about his future.
"The fans will understand my decision for I have always been honest, coherent and up front. They will forgive my not continuing," he added ahead of the final on May 18.
Earlier on Tuesday, Radio Renascenca reported, without citing sources, that Domingos had signed a two-year deal with Sporting, who have had a very disappointing season.
Sporting manager Paulo Sergio quit in February with Jose Couceiro, a former coach who joined the Lisbon club as managing director in December, taking over for the rest of the season.
The 42-year-old Domingos said the Europa League final against Porto, for whom he scored over 100 goals in a long career as a lethal striker, will be "the game of my life".
With most observers considering Andre Villas Boas' rampant league champions Porto as favourites, Domingos said his team's underdog status would bring them some support.
"It's like when we watch films when we are young, we always want the small guy to beat the big guy. It's a bit like that, but we know we will face a team with a lot of international experience, so we know it will be tough," he said.
Domingos added he does not plan to make too many changes to his team for the first all-Portuguese European final.
"We have to keep the same routines, though knowing it is a final. We have shown in other rounds against big teams that we can succeed and want to do the same now," he said.
Braga beat Sevilla and Celtic to reach the Champions League group stage, where they posted wins against Arsenal and Partizan Belgrade before dropping into the Europa League.
They knocked out former European champions Liverpool and Benfica on the way to this month's final.
