After a 4-0 hammering at home to Atalanta last weekend, Juve lost 3-0 at Fiorentina which leaves Motta's side fifth in the Serie A standings and the manager under increasing pressure.
"In these moments we must all stay united, we all come out of difficulties together," Giuntoli told Sky Sports.
"We are very sorry, we have had a year with ups and downs but we had never played two games so below par, but we are convinced we can come out of this all together."
When asked if this meant continuing with Motta in charge, Giuntoli had no doubts: "Certainly," he said.
"We started from a project in which we counted on having difficulties, lowering salaries and everything else, we must think about nothing but our primary goal, which is to qualify for the Champions League."
Giuntoli is not getting carried away after two bad performances, just as the club did not when they began the season with two 3-0 wins over Como and Hellas Verona.
"We try to analyse in a lucid way what has happened in recent weeks. Let's not forget that the media, after Verona, had us as a potential winner of the league," Giuntoli said.
"We need balance, we cannot go from the stars to the stables. In the next few days we will try, with a clear mind, to move forward.
"We have to have balance, on and off the pitch. Until two games ago, the team had the best defence in the league, conceding four or three goals means that we have lost balance."
Motta was adamant he will not throw in the towel despite the difficulties in his first season at the club, with Juve out of the title race, the Champions League and Coppa Italia.
"It would be too easy to do it. I don't like easy things," Motta said when asked about the possibility of resigning.
"We need to win, we have to find a way to get the points we need for our goal, which is to be in the top four of the championship.
"It's a bit like a continuation of the last game, it's the same story. We start well, then at the first difficulty, like against Atalanta, we were unable to react."