The manager penned a new four-year deal this week and Gabriel Agbonlahor signed his own contract extension last week.
New England international Delph and skipper Vlaar only have a year left on their deals at Villa Park.
Defender Vlaar was heavily linked with Southampton in the summer after an impressive World Cup with Holland.
And, after Lambert committed himself to the club until 2018, he wants to tie his key players down.
"That's the next agenda, to speak to those lads and see if we can do things," he said.
"Other lads have re-signed again and if we can get those lads tied up that's what we'll try to do."
Villa host Arsenal on Saturday second in the Barclays Premier League with Vlaar a major doubt with the calf injury which forced him to miss the 1-0 win at Liverpool at the weekend.
Christian Benteke is also still sidelined but has trained this week without trouble.
The striker returned on Monday following five months out with a ruptured Achilles and Lambert insisted he is not guaranteed a starting spot once he is fit.
"It's massive for him, he has trained all week and had no adverse reaction
He has got to work hard to try to get back in the side," he said.
"Gabby and Andi (Weimann) are playing great, the front lads are on form, but this week Christian has done really well.
"I'm not sure (when he'll be back), it's his first week
He trained this morning and speaking to him after training he felt good."
Fellow forward Libor Kozak will have a routine check-up at hospital on Friday as he recovers from the broken leg he suffered in January.
Source : PA