Possibility of Human cloning
Cloning of animals typically involves:


Taking nucleus from healthy adult cell of animal to clone
Taking a healthy egg and replace the egg's nucleus with nucleus from source animal.
Implanting egg in female, stimulating the pregnancy process.


This same process should work on humans BUT:


"Is it really possible to create humans in lab?" No. Animal cloning doesn't work this way, so human cloning wouldn't either. Animals aren't "created" in lab. The one artificial step is the modifying the nucleus of the egg cell before the pregnancy process initiates. The rest of the egg->embryo->infant pregnancy process is traditional nature and there is no working lab process available to replace natural pregnancies.
Cloning animals is very high risk, it involves lots of trial and error, and involves lots of mistakes, botched pregnancies, abortions, and birth defects. The core concept of replacing the nucleus in an egg cell makes sense, but the practical reality of that procedure involves cell damage and pregnancy risks. With non-human animals, no one cares. With humans, purposefully causing lots of botched pregnancies, miscarriages, and birth defects will make most people squeamish.
Donor Eggs: If the process worked perfectly, a single donor egg would suffice. Since the process doesn't work perfectly, many donor eggs are required. Getting those donor eggs is a very invasive process that I would not want my wife, sisters, or daughters to subject themselves to. With lab animals, who cares, scientists can be as invasive as they want, and harvest all the eggs that they need. Humans have rights which really impedes this type of risky work.


Today, cloning humans is possible, but at prohibitively high cost and risk. It is inevitably going to happen, but the costs and risks will impede its popularity. Process improvements that deliver more safety and reliability will allow human cloning to become more popular.

UPDATE: "Why cant it be attempted..?" It definitely is being attempted. Panayiotis Zavos is one doctor who has been very public about his attempts to clone humans:

"In April 2009, he claimed to have cloned 14 human embryos and transferred 11 of those to wombs."

AFAIK, none of these efforts led to a live birth. I'm sure other doctors have attempted and even more are considering it and waiting until it's a little more practical and realistic.