The Celtics took a 3-2 lead in the Conference Finals with Wednesday’s 93-80 win in Miami, with Butler shooting four of 18 from the field for his 13 points.
Butler had exited Game 3 early due to knee inflammation and has only scored eight, six and 13 in his past three games.
“We’re not making excuses for anything. We’re not deflecting anything,” Spoelstra told reporters after the defeat.
“We lost the game today. We had a tough loss in Boston. We’re still alive.”
Butler’s shooting was alarming but he was not alone, with the Heat going at 16 per cent from three-point range, making only seven of 45 for the game.
Butler managed only one of five from beyond the arc, while he only got to the free-throw line four times.
“He had some really good clean looks,” Spoelstra said about Butler. “He missed three or four that were right at the rim and in the circle and other pull-ups.”
Kyle Lowry failed to trouble the scorers, shooting none of six from the field for the game, while Max Strus only managed four points, all from the free-throw line.
“I don’t think either of them played outside of themselves,” Spoelstra said.
“I know how ignitable our guys are, that could turn in a hurry. particularly on the road.”
“We just have to stay the course. even as disappointing and frustrating as this game can be, we get on to Boston and come together and figure that one out.”
The Celtics shot at 30.3 per cent from beyond the arc, having trailed 42-37 at half-time. Jayson Tatum scored 22 points with 12 rebounds and nine assists, while Jaylen Brown had 25 points including five triples.
Boston head coach Ime Udoka said: “It was big to be that close and know we didn’t play our best in the first half, we talked about flipping he script and playing a really clean second half.
“We did that, JT (Tatum) and JB (Brown) got it going. both those guys almost triple-doubled.”