The Catalans, who visited Japan and United States of America during their pre-season have won just three out of six LaLiga games thus far, suffering two defeats and Pique has blamed the wobbling performances witnessed by the side on their stressful pre-season campaign.
"The pre-season did not help at all to start well in the competition, a lot of travel and little training," Pique said.
"Many of us notice it and we don't have the tone yet, not only Messi, but we must continue because we are forced to win, it is a setback.
"Look now what has happened to Messi, but there are no excuses, in the team there are qualified people to replace him and move on, although we hope he will be out as short as possible.
"There are quite a few players who have not achieved the tone because it is what it is. I do not know the severity of his [Messi's] injury and I hope it is as little as possible.
"There are no excuses. Although it is the best there are no excuses in Barcelona, although the pre-season was not the best."
Defeating Villarreal 2-1 at the Camp Nou on Tuesday, Pique believes winning the maximum points was vital for Barcelona as they currently sit fourth in the table, one point adrift Real Madrid, who are yet to play their sixth game against Osasuna on Wednesday.
"It was important to win so as not to disengage from the top teams. With both goals and Leo's injury, the team has pulled back a bit," he said.
"They have advanced the lines and marked us. In the second half, it was difficult."
