Barca face Madrid in the first leg of the Copa del Rey semi-finals and Valverde said Messi had felt some discomfort against Valencia, after scoring twice to salvage his team a point.
"We have to wait until tomorrow to do the tests to see how he is, like the other players," Valverde said. "I don't know too much more. We hope he can recover, just like the others."
Asked what the problem was, Valverde said: "I don't know, I would like to tell you more but I don't know exactly.
"He had a little problem, as some of the others will have too. We will wait to see what the doctors tell us when they do the tests and we will look at it. I cannot guess anything but we imagine that it can't be too bad."
Messi's absence at the Camp Nou would be a blow to Barcelona, particularly with the Argentinian in such blistering form.
His double against Valencia means he has now scored in nine consecutive matches, while registering a total of 12 goals in that period.
Barca might also be cautious, given they have a testing month of fixtures ahead. They play Madrid three times in the next four weeks, twice in the cup and once in La Liga.
There will also be two legs against Lyon to negotiate in the last 16 of the Champions League.