Chelsea fell to defeat in front of their own fans at Stamford Bridge on Saturday.
With Tammy Abraham out injured, Chelsea turned to Giroud over Michy Batshuayi to start against the Hammers, but the move from Lampard did not really work.
West Ham ended up causing the shock of the Premier League weekend by beating Chelsea at Stamford Bridge, and Giroud was ineffective in the contest.
The French striker failed to finish some good chance which came his way, and he also struggled to become fully involved in the match.
“It was a difficult game for him,” Lampard admitted. “He didn’t get enough of the ball and then the couple of chances he had didn’t go in for him.
“It was a tough match for him but he wasn’t the only one who came into the team and the performance was slightly off it. It was not the easiest game.”
Giroud’s future at Chelsea is already up in the air, so his latest showing is unlikely to have done much to convince that he should be kept around.
The experienced striker could now face dropping to the bench in midweek, regardless of whether Abraham is fit again or not.
Chelsea have been in good form of late, but they are now winless in three and Lampard will be keen to ensure his side get the taste of victory again sooner rather than later.
Chelsea’s next chance to pick up three points will be on Wednesday evening, when they take on Aston Villa.