The Cherries travelled to Villa Park hoping to get a respectable result against Unai Emery’s men, however, they were hit for four despite some strings of positive performance.
“It’s a really difficult one to take,” Cook told the club website.
“We came here wanting to show a reaction and compete, but Villa punished us when they got their chances. They’re a strong side, and we know we weren’t at our best today.
“We’ve had setbacks before and always responded. This group sticks together - we’ll review it, work hard in training this week, and make sure we come back stronger.
“We know what we’re capable of when we’re at our best. It’s about refocusing, learning from today, and putting things right against West Ham when everyone returns from the international break."