The law on hair pulling was relaxed at the start of this season so that not every incident is a red card, after three sendings-off last season.
Yann Gboho had put Coventry ahead after the break. The visitors felt they should have had a first-half penalty.
Officials now consider excessive force and intent. Not all contact with the hair is an offence.
For a penalty, Tarkowski’s actions needed only to be a foul, not violent conduct, Lampard argued.
A camera level with the edge of the penalty area appeared to show the contact outside the box, so VAR could not award a free-kick.
He added that if the rule remains that it is a foul, he felt it was a foul.
Lampard said it looked as if Tarkowski’s arm moved to pull the hair and that should have brought a VAR intervention. “They’re saying it’s not enough of a pull and I think it’s a hard area to be in,” he said. Lampard still called the rule ridiculous and said he could not understand why it had not been fixed completely.
“Taiwo for me on the line of the box is a penalty,” Lampard said.