I have recently changed my bikes camshaft and rocker arms from a recognized mechanic. But after that I continuously hear clicking noise increased from the head sections of engine. Noise continuously comes doesn't matter if engine is idle or running.
Perfectly normal if there's a slight 'tick' or 'clicking' sound. The clearance between the cam lobe and tappet is a little greater than normal, and this exercise simply helps the new parts to seat/wear in with the old parts without putting too much stress on either. More precautionary than mandatory for the local engineers. For myself, I like the sound of valves talking away on a cold engine. Only helps to know they're breathing freely.
Just pay the mechanic another visit after running in a couple hundred kilometers. Appropriately a 'recognized' mechanic would be expected of telling you to do just that.
I've also heard that Suzuki and Kawasaki engines have this sound is this true? And after engine settles down with new parts and still that noise is there noticeable then can any alternation be done to keep it down?
False information. Both the mentioned manufacturers have been flawless and legendary when it comes to engine designs in the past decade or two. In my honest opinion, it never is the engine or the manufacturers mistake, rather its always the people that end up handling it.
I have previously bought new Suzuki in 2007 and also noticed that that tickling noise is rather louder than I've listened on other bikes. That was why I am in that view about Suzuki can't say about the same for Kawasaki just heard that it does that too.