Gresini rider Bastianini and his future factory Ducati team-mate Bagnaia engaged in a tense duel for the win at Misano last Sunday.
The pair came close to a collision on the final lap into Turn 4, but both emerged unscathed and ran line astern into the last turn.
Bastianini got a good run on Bagnaia on the drag to the chequered flag, but missed out on the win by just 0.034 seconds.
Ducati has told its riders it will not deploy team orders if the chance of a victory is there while fighting with its title hope Bagnaia, but Bastianini felt a desperate lunge at the last corner to try and overtake his factory team counterpart would have been foolish.
“Me, I tried with all my potential to do the best to win that race,” Bastianini said when asked about his battle with Bagnaia. “But Pecco made a very good lap.
“I tried in Turn 4 and when I went outside I tried again, and in the last corner for me it was crazy to try to overtake Pecco because we could crash together.
“Well, I tried a little bit with the acceleration with the bike. But it’s OK.”
Bastianini struggled in the early laps as he lacked grip on his 2021-spec Ducati, but would up his pace in the second half of the grand prix to chase down Bagnaia in the closing stages.
His mistake under braking for Turn 4 on the last lap ultimately proved costly as it gave Bagnaia crucial metres with which to hold on to the win on the run to the line.
Speaking about that Turn 4 moment, Bastianini said he simply out-braked himself.
“Yeah, I braked so strong and I tried to overtake in that corner but I was a little bit late and I preferred to go outside,” Bastianini said.
“At the end I tried again at the last corner but Pecco braked very late and it was impossible for me today.”
