Hello
I wonder if anyone can give me advice.
I have a 7 month old Staff that is showings aggression towards puupies. Can I kurb this behaviour?
He is fine with older dogs but he snarls and goes for the attack when on the lead. He used to be off the lead but he sis attack a 5 months lab, not seirously but enough to scare me.
I hate keep ing him on a lead as he loves to run around. What can I do!!

Have you taken him to a training class? Not only to learn some obedience but to also get socialisation with other dogs his age. He is young but he needs to learn that this behaviour is unacceptable by yourself and you need to teach him now otherwise you will have an unruly dog which you can never trust of the lead.
I would not let him off the lead until you have a trained a good recall with him. Bear in mind he is young and the world is an interesting place with lots of distractions. Look at using a flexi lead (only in open spaces) It would give him a bigger area to run under control and they are great for practising recall with.
If you look on here there are some good tips on recall training.
Is he having a go at all pups or only male ones. He is at the age where his hormones are raging and he's starting to show his dominance. Have you had him castrated? I'm not advocating it just asking the question.