The Biancazzurri raced into a 2-0 lead on Sunday, courtesy of Felipe Anderson’s first-half brace, but Mateo Kovacic and Rodrigo Palacio struck back for Inter.
“It’s a shame,” Pioli told Gazzetta dello Sport. “We should have kept the ball more and controlled possession, but Inter were extremely aggressive.
“Obviously winning 2-0 at half-time we wanted to win, but we misplaced a few passes, poor clearances and were unable to get the victory.”
The result leaves Lazio level on 27 points with Sampdoria and Napoli, but the Biancazzurri occupy third place due to their superior goal difference.
Despite the disappointment of failing to move clear in the final Champions League place, Pioli paid tribute to Inter’s fighting spirit.
“Kovacic’s fantastic goal really changed the game and it gave Inter hope,” he added. “Inter were determined not to lose at home and they succeeded.”
Lazio, who finished ninth in Serie A last season, face a stern test of their credentials when the action resumes in January, with games against Sampdoria, Roma, Napoli and AC Milan kicking off 2015.
“Now we need to recharge our batteries and go forward into January with more important games,” Pioli said. “We have a good position in the table but we know it is only a stepping stone.
“We said from the start our objective was to finish in the top five.
“If we look back to where we started and what happened last season, the team has worked very well to be here.”