Rossi underwent surgery in Ancona, in eastern Italy, on September 1, a day after a crash in training, discharging himself from hospital the following day.
The 38-year-old rode his first couple of laps around the Misano circuit on Monday before the session was cut short by rain, his team said.
"The evaluation of Rossi's physical condition was inconclusive," the team said with a decision expected midweek on whether the veteran will attempt to take part in this weekend's Aragon MotoGP.
If Rossi cannot compete his place should be taken by Dutch Superbike rider Michael van der Mark.
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Rossi missed the San Marino Grand Prix but remains fourth in the standings, 42 points behind world champion Marc Marquez of Spain and Italy's Andrea Dovizioso with five rounds to go.
Rossi won the Dutch MotoGP in Assen in June to reignite his dream of a 10th world title and is fighting to be fit for the final races of the season which finishes on November 12 in Valencia.