He was annoyed with bookmakers who had set odds on Lawrence's successor at Ninian Park after the Bluebirds' promotion drive had stuttered in recent weeks.
"Lennie is very important, he will be with us this summer and well beyond next summer even if he loses every game from now until the end of the season," Hammam told BBC Sport Wales.
Speculation was rife when former Cardiff hero John Toshack turned up at Ninian Park on Monday, but Hammam categorically denied any connection, insisting that the out-of-work manager is a regular visitor and a big fan of the club.
The colourful Cardiff owner also spoke out on the discontented crowds who, it has been claimed, are affecting the Bluebirds' home form.
He said that he could understand their booing as a sign of their passion for the club, but that such fans were doing the team no favours and they should follow match commentary from home rather than attending the games.
"We don't want losers. We are in a war and we need people who can handle that," he said.
"Lennie is a top-notch man, very calm, considerate, hard-working and experienced."